%% Books
@book{fds375046,
Author = {R. Boussarie and et.al.},
Title = {TMD Handbook},
Year = {2023},
url = {https://arxiv.org/abs/2304.03302},
Key = {fds375046}
}
%% Papers Published
@article{fds287680,
Author = {Mehen, T and Stewart, IW},
Title = {A momentum subtraction scheme for two-nucleon effective
field theory},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {445},
Number = {3-4},
Pages = {378-386},
Publisher = {Elsevier BV},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1016/S0370-2693(98)01470-1},
Abstract = {We introduce a momentum subtraction scheme which obeys the
power counting of Kaplan, Savage, and Wise (KSW), developed
for systems with large scattering lengths, a. Unlike the
power divergence subtraction scheme, coupling constants in
this scheme obey the KSW scaling for μR > 1/a. We comment
on the low-energy theorems derived by Cohen and Hansen. We
conclude that there is no obstruction to using perturbative
pions for momenta p > mπ. © 1999 Elsevier Science B.V. All
rights reserved.},
Doi = {10.1016/S0370-2693(98)01470-1},
Key = {fds287680}
}
@article{fds287693,
Author = {Hammer, HW and Mehen, T},
Title = {A renormalized equation for the three-body system with
short-range interactions},
Journal = {Nuclear Physics A},
Volume = {690},
Number = {4},
Pages = {535-546},
Publisher = {Elsevier BV},
Year = {2001},
Month = {July},
url = {http://dx.doi.org/10.1016/S0375-9474(00)00710-7},
Abstract = {We study the three-body system with short-range interactions
characterized by an unnaturally large two-body scattering
length. We show that the off-shell scattering amplitude is
cutoff independent up to power corrections. This allows us
to derive an exact renormalization group equation for the
three-body force. We also obtain a renormalized equation for
the off-shell scattering amplitude. This equation is
invariant under discrete scale transformations. The
periodicity of the spectrum of bound states originally
observed by Efimov is a consequence of this symmetry. The
functional dependence of the three-body scattering length on
the two-body scattering length can be obtained analytically
using the asymptotic solution to the integral equation. An
analogous formula for the three-body recombination
coefficient is also obtained. © 2001 Elsevier Science
B.V.},
Doi = {10.1016/S0375-9474(00)00710-7},
Key = {fds287693}
}
@article{fds349541,
Author = {Fleming, S and Makris, Y and Mehen, T},
Title = {An effective field theory approach to quarkonium at small
transverse momentum},
Journal = {Journal of High Energy Physics},
Volume = {2020},
Number = {4},
Year = {2020},
Month = {April},
url = {http://arxiv.org/abs/arXiv:1910.03586},
Abstract = {In this work we apply effective field theory (EFT) to
observables in quarkonium production and decay that are
sensitive to soft gluon radiation, in particular
measurements that are sensitive to small transverse
momentum. Within the EFT framework we study χQ decay to
light quarks followed by the fragmentation of those quarks
to light hadrons. We derive a factorization theorem that
involves transverse momentum distribution (TMD)
fragmentation functions and new quarkonium TMD shape
functions. We derive renormalization group equations, both
in rapidity and virtuality, which are used to evolve the
different terms in the factorization theorem to resum large
logarithms. This theoretical framework will provide a
systematic treatment of quarkonium production and decay
processes in TMD sensitive measurements.},
Doi = {10.1007/JHEP04(2020)122},
Key = {fds349541}
}
@article{fds322009,
Author = {Yao, X and Mehen, T and Müller, B},
Title = {An effective field theory approach to the stabilization of
8Be in a QED plasma},
Journal = {Journal of Physics G: Nuclear and Particle
Physics},
Volume = {43},
Number = {7},
Pages = {07LT02-07LT02},
Publisher = {IOP Publishing},
Year = {2016},
Month = {May},
url = {http://dx.doi.org/10.1088/0954-3899/43/7/07LT02},
Abstract = {We use effective field theory to study the a-a resonant
scattering in a finitetemperature QED plasma. The static
plasma screening effect causes the resonance state 8Be to
live longer and eventually leads to the formation of a bound
state when mD ≳ 0.3 MeV. We speculate that this effect may
have implications on the rates of cosmologically and
astrophysically relevant nuclear reactions involving a
particles.},
Doi = {10.1088/0954-3899/43/7/07LT02},
Key = {fds322009}
}
@article{fds322010,
Author = {Bain, R and Dai, L and Hornig, A and Leibovich, AK and Makris, Y and Mehen,
T},
Title = {Analytic and Monte Carlo studies of jets with heavy mesons
and quarkonia},
Journal = {Journal of High Energy Physics},
Volume = {2016},
Number = {6},
Pages = {1-28},
Publisher = {Springer Nature},
Year = {2016},
Month = {June},
url = {http://dx.doi.org/10.1007/JHEP06(2016)121},
Abstract = {Abstract: We study jets with identified hadrons in which a
family of jet-shape variables called angularities are
measured, extending the concept of fragmenting jet functions
(FJFs) to these observables. FJFs determine the fraction of
energy, z, carried by an identified hadron in a jet with
angularity, τa. The FJFs are convolutions of fragmentation
functions (FFs), evolved to the jet energy scale, with
perturbatively calculable matching coefficients.
Renormalization group equations are used to provide resummed
calculations with next-to-leading logarithm prime (NLL’)
accuracy. We apply this formalism to two-jet events in
e+e− collisions with B mesons in the jets, and three-jet
events in which a J/ψ is produced in the gluon jet. In the
case of B mesons, we use a phenomenological FF extracted
from e+e− collisions at the Z0 pole evaluated at the scale
μ = mb. For events with J/ψ, the FF can be evaluated in
terms of Non-Relativistic QCD (NRQCD) matrix elements at the
scale μ = 2mc. The z and τa distributions from our NLL’
calculations are compared with predictions from monte carlo
event generators. While we find consistency between the
predictions for B mesons and the J/ψ distributions in τa,
we find the z distributions for J/ψ differ significantly.
We describe an attempt to merge PYTHIA showers with NRQCD
FFs that gives good agreement with NLL’ calculations of
the z distributions.},
Doi = {10.1007/JHEP06(2016)121},
Key = {fds322010}
}
@article{fds287622,
Author = {Fleming, S and Leibovich, AK and Mehen, T and Rothstein,
IZ},
Title = {Anomalous dimensions of the double parton fragmentation
functions},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {87},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2013},
Month = {April},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/arXiv:1301.3822},
Abstract = {Double parton fragmentation is a process in which a pair of
partons produced in the short-distance process hadronize
into the final state hadron. This process is important for
quarkonium production when the transverse momentum is much
greater than the quark mass. Resummation of logarithms of
the ratio of these two scales requires the evolution
equations for double parton fragmentation functions (DPFF).
In this paper we complete the one-loop evaluation of the
anomalous dimensions for the DPFF. We also consider possible
mixing between the DPFF and single parton power suppressed
gluon fragmentation and show that such effects are
subleading. © 2013 American Physical Society.},
Doi = {10.1103/PhysRevD.87.074022},
Key = {fds287622}
}
@article{fds287659,
Author = {Braaten, E and Jia, Y and Mehen, T},
Title = {B Production Asymmetries in Perturbative
QCD},
Journal = {Phys. Rev. D66, 034003},
Volume = {66},
Number = {3},
Pages = {9},
Publisher = {American Physical Society (APS)},
Year = {2002},
ISSN = {0556-2821},
url = {http://arxiv.org/abs/hep-ph/0108201},
Abstract = {This paper explores a new mechanism for B production in
which a b quark combines with a light parton from the
hard-scattering process before hadronizing into the B
hadron. This recombination mechanism can be calculated
within perturbative QCD up to a few nonperturbative
constants. Though suppressed at large transverse momentum by
a factor Lambda_QCD m_b/p_t^2 relative to b quark
fragmentation production, it can be important at large
rapidities. A signature for this heavy-quark recombination
mechanism in proton-antiproton colliders is the presence of
rapidity asymmetries in B cross sections. Given reasonable
assumptions about the size of nonperturbative parameters
entering the calculation, we find that the asymmetries are
only significant for rapidities larger than those currently
probed by collider experiments.},
Doi = {10.1103/PhysRevD.66.034003},
Key = {fds287659}
}
@article{fds287663,
Author = {Mehen, T},
Title = {Charm production asymmetries from heavy-quark
recombination},
Journal = {Journal of Physics G: Nuclear and Particle
Physics},
Volume = {30},
Number = {1},
Pages = {S295-S304},
Publisher = {IOP Publishing},
Year = {2004},
Month = {January},
url = {http://arxiv.org/abs/hep-ph/0306178},
Abstract = {Charm asymmetries in fixed-target hadroproduction
experiments are sensitive to power corrections to the QCD
factorization theorem for heavy quark production. A power
correction called heavy-quark recombination has recently
been proposed to explain these asymmetries. In heavy-quark
recombination, a light quark or antiquark participates in a
hard scattering which produces a charm-anticharm quark pair.
The light quark or antiquark emerges from the scattering
with small momentum in the rest frame of the charm quark,
and together they hadronize into a charm particle. The cross
section for this process can be calculated within
perturbative QCD up to an overall normalization. Heavy-quark
recombination explains the observed D meson and ΛC
asymmetries with a minimal set of universal nonperturbative
parameters.},
Doi = {10.1088/0954-3899/30/1/035},
Key = {fds287663}
}
@article{fds287673,
Author = {Braaten, E and Jia, Y and Mehen, T},
Title = {Charm-anticharm asymmetries in photoproduction from
heavy-quark recombination},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {66},
Number = {1 II},
Pages = {140031-1400310},
Year = {2002},
ISSN = {0556-2821},
url = {http://arxiv.org/abs/hep-ph/0111296},
Abstract = {The asymmetries between charm and anticharm mesons observed
in fixed-target photoproduction experiments are an order of
magnitude larger than the asymmetries predicted by
conventional perturbative QCD. We show that these charm
meson asymmetries can be explained by a heavy-quark
recombination mechanism for heavy meson production. In this
process, a charm quark combines with a light antiquark from
the hardscattering process and they subsequently hadronize
into a state including the charm meson. This recombination
mechanism can be calculated within perturbative QCD up to
some nonperturbative constants. After using symmetries of
QCD to reduce the number of free parameters to two, we
obtain a good fit to all the data on the asymmetries for
charmed mesons from the E687 and E691 experiments.},
Doi = {10.1103/PhysRevD.66.014003},
Key = {fds287673}
}
@article{fds287637,
Author = {Hu, J and Mehen, T},
Title = {Chiral Lagrangian with heavy quark-diquark
symmetry},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {73},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2006},
Month = {March},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/hep-ph/0511321},
Abstract = {We construct a chiral Lagrangian for doubly heavy baryons
and heavy mesons that is invariant under heavy quark-diquark
symmetry at leading order and includes the leading O(1/mQ)
symmetry violating operators. The theory is used to predict
the electromagnetic decay width of the J=32 member of the
ground state doubly heavy baryon doublet. Numerical
estimates are provided for doubly charm baryons. We also
calculate chiral corrections to doubly heavy baryon masses
and strong decay widths of low lying excited doubly heavy
baryons. © 2006 The American Physical Society.},
Doi = {10.1103/PhysRevD.73.054003},
Key = {fds287637}
}
@article{fds287653,
Author = {Kim, C and Mehen, T},
Title = {Color octet scalar bound states at the LHC},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {79},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2009},
Month = {March},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/0903.3668},
Abstract = {One possible extension of the standard model scalar sector
includes SU(2)L doublet scalars that are color octets rather
than singlets. We focus on models in which the couplings to
fermions are consistent with the principle of minimal flavor
violation, in which case these color-octet scalars couple
most strongly to the third generation of quarks. When the
Yukawa coupling of color-octet scalars to standard model
fermions is less than unity, these states can live long
enough to bind into color-singlet spin-0 hadrons, which we
call octetonia. In this paper, we consider the phenomenology
of octetonia at the Large Hadron Collider. Predictions for
their production via gluon-gluon fusion and their two-body
decays into standard model gauge bosons, Higgs bosons, and
t̄t are presented. © 2009 The American Physical
Society.},
Doi = {10.1103/PhysRevD.79.035011},
Key = {fds287653}
}
@article{fds287685,
Author = {Mehen, T and Stewart, IW and Wise, MB},
Title = {Conformal Invariance for Non-Relativistic Field
Theory},
Journal = {Phys. Lett. B},
Volume = {474},
Number = {1-2},
Pages = {145-152},
Publisher = {Elsevier BV},
Year = {2000},
url = {http://dx.doi.org/10.1016/s0370-2693(00)00006-x},
Abstract = {Momentum space Ward identities are derived for the amputated
n-point Green's functions in 3+1 dimensional
non-relativistic conformal field theory. For n=4 and 6 the
implications for scattering amplitudes (i.e. on-shell
amputated Green's functions) are considered. Any scale
invariant 2-to-2 scattering amplitude is also conformally
invariant. However, conformal invariance imposes constraints
on off-shell Green's functions and the three particle
scattering amplitude which are not automatically satisfied
if they are scale invariant. As an explicit example of a
conformally invariant theory we consider non-relativistic
particles in the infinite scattering length
limit.},
Doi = {10.1016/s0370-2693(00)00006-x},
Key = {fds287685}
}
@article{fds287645,
Author = {Fleming, S and Mehen, T},
Title = {Decay of the X(3872) into χ cJ and the operator
product expansion in effective field theory},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {85},
Number = {1},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {January},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.85.014016},
Abstract = {We consider a low-energy effective theory for the X(3872)
(XEFT) that can be used to systematically analyze the decay
and production of the X(3872) meson, assuming that it is a
weakly bound state of charmed mesons. In a previous paper,
we calculated the decays of X(3872) into χ cJ plus pions
using a two-step procedure in which Heavy Hadron Chiral
Perturbation Theory (HHχPT) amplitudes are matched onto
XEFT operators and then X(3872) decay rates are calculated
using these operators. The procedure leads to IR divergences
in the three-body decay X(3872)→χ cJππ when virtual D
mesons can go on shell in tree level HHχPT diagrams. In
previous work, we regulated these IR divergences with the D
*0 width. In this work, we carefully analyze X(3872)→χ
cJπ0 and X(3872)→χ cJππ using the operator product
expansion in XEFT. Forward scattering amplitudes in HHχPT
are matched onto local operators in XEFT, the imaginary
parts of which are responsible for the decay of the X(3872).
Here we show that the IR divergences are regulated by the
binding momentum of the X(3872) rather than the width of the
D *0 meson. In the operator product expansion, these IR
divergences cancel in the calculation of the matching
coefficients so the correct predictions for the X(3872)→χ
c1ππ do not receive enhancements due to the width of the D
*0. We give updated predictions for the decay X(3872)→χ
c1ππ at leading order in XEFT. © 2012 American Physical
Society.},
Doi = {10.1103/PhysRevD.85.014016},
Key = {fds287645}
}
@article{fds287667,
Author = {Mehen, T and Schat, C},
Title = {Determining pentaquark quantum numbers from strong
decays},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {588},
Number = {1-2},
Pages = {67-73},
Publisher = {Elsevier BV},
Year = {2004},
Month = {May},
url = {http://arxiv.org/abs/hep-ph/0401107},
Abstract = {Assuming that the recently observed Θ+ and Ξ- are members
of an anti-decuplet of SU(3), decays to ground state baryons
and mesons are calculated using an effective Lagrangian
which incorporates chiral and SU(3) symmetry. We consider
the possible quantum number assignments JΠ=12±,32± and
calculate ratios of partial widths. The branching ratios of
exotic cascades can be used to discriminate between even and
odd parity pentaquarks. © 2004 Published by Elsevier
B.V.},
Doi = {10.1016/j.physletb.2004.03.039},
Key = {fds287667}
}
@article{fds287631,
Author = {Braaten, E and Hammer, H-W and Mehen, T},
Title = {Dilute Bose-Einstein condensate with large scattering
length.},
Journal = {Physical review letters},
Volume = {88},
Number = {4},
Pages = {040401},
Year = {2002},
Month = {January},
url = {http://arxiv.org/abs/cond-mat/0108380},
Abstract = {We study a dilute Bose gas of atoms whose scattering length
a is large compared to the range of their interaction. We
calculate the energy density E of a homogeneous
Bose-Einstein condensate (BEC) to second order in the
low-density expansion, expressing it in terms of a and a
second parameter Lambda* that determines the low-energy
observables in the three-body sector. The second-order
correction to E has a small imaginary part that reflects the
instability due to three-body recombination. In the case of
a trapped BEC with large negative a, we calculate the
coefficient of the three-body mean-field term in E in terms
of a and Lambda*. It can be very large if there is an Efimov
state near threshold.},
Doi = {10.1103/physrevlett.88.040401},
Key = {fds287631}
}
@article{fds350891,
Author = {Mehen, T and Mohapatra, A},
Title = {Doubly heavy baryons and corrections to heavy quark-diquark
symmetry prediction for hyperfine splitting},
Journal = {Proceedings of the 2019 Meeting of the Division of Particles
and Fields of the American Physical Society, DPF
2019},
Year = {2019},
Month = {January},
Abstract = {In the mQ → ∞ limit, the hyperfine splittings in the
ground state doubly heavy baryons (QQq) and single heavy
antimesons (Q̄q) are related by heavy quark-diquark
symmetry (HQDQ) as the light degrees of freedom in both the
hadrons are expected to have identical configurations. In
this article, working within the framework of
nonrelativistic QCD (NRQCD), we study the perturbative and
nonperturbative corrections to the HQDQ symmetry hyperfine
splitting relation that scale as O (α2s) and Λ2QCD/m2Q
respectively. In the extreme heavy quark limit, the
perturbative corrections to hyperfine splitting of doubly
charm or bottom baryons are a few percent or smaller. The
nonperturbative corrections to hyperfine splitting are of
order 10% in the case of doubly charm baryons and 1% or
smaller in doubly bottom baryons.},
Key = {fds350891}
}
@article{fds350863,
Author = {Mehen, T and Mohapatra, A},
Title = {Doubly heavy baryons and corrections to heavy quark-diquark
symmetry prediction for hyperfine splitting},
Journal = {Proceedings of the 2019 Meeting of the Division of Particles
and Fields of the American Physical Society, DPF
2019},
Year = {2019},
Month = {January},
url = {http://arxiv.org/abs/arXiv:1910.05337},
Abstract = {© 2019 SLAC National Accelerator Laboratory. All rights
reserved. In the mQ → ∞ limit, the hyperfine splittings
in the ground state doubly heavy baryons (QQq) and single
heavy antimesons (Q̄q) are related by heavy quark-diquark
symmetry (HQDQ) as the light degrees of freedom in both the
hadrons are expected to have identical configurations. In
this article, working within the framework of
nonrelativistic QCD (NRQCD), we study the perturbative and
nonperturbative corrections to the HQDQ symmetry hyperfine
splitting relation that scale as O (α2s) and Λ2QCD/m2Q
respectively. In the extreme heavy quark limit, the
perturbative corrections to hyperfine splitting of doubly
charm or bottom baryons are a few percent or smaller. The
nonperturbative corrections to hyperfine splitting are of
order 10% in the case of doubly charm baryons and 1% or
smaller in doubly bottom baryons.},
Key = {fds350863}
}
@article{fds287662,
Author = {Mehen, T and Tiburzi, BC},
Title = {Doubly heavy baryons and quark-diquark symmetry in quenched
and partially quenched chiral perturbation
theory},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {74},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2006},
Month = {September},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/hep-lat/0607023},
Abstract = {We extend the chiral Lagrangian with heavy quark-diquark
symmetry to quenched and partially quenched theories. These
theories are used to derive formulas for the chiral
extrapolation of masses and hyperfine splittings of double
heavy baryons in lattice QCD simulations. A quark-diquark
symmetry prediction for the hyperfine splittings of heavy
mesons and doubly heavy baryons is rather insensitive to
chiral corrections in both quenched and partially quenched
QCD. Extrapolation formulas for the doubly heavy baryon
electromagnetic transition moments are also determined for
the partially quenched theory. © 2006 The American Physical
Society.},
Doi = {10.1103/PhysRevD.74.054505},
Key = {fds287662}
}
@article{fds43963,
Author = {S. Fleming and T. Mehen},
Title = {Doubly Heavy Baryons, Heavy Quark-Diquark Symmetry and
NRQCD},
Journal = {Phys. Rev. D 73, 034502},
Year = {2006},
url = {http://arxiv.org/abs/hep-ph/0509313},
Abstract = {In the heavy quark limit, properties of heavy mesons and
doubly heavy baryons are related by heavy quark-diquark
symmetry. This problem is reanalyzed in the framework of
Non-Relativistic QCD (NRQCD). We introduce a novel method
for deriving Potential NRQCD (pNRQCD) Lagrangians for
composite fields from vNRQCD, which contains quarks and
antiquarks as explicit degrees of freedom and maintains
manifest power counting in the velocity via a label
formalism. A Hubbard-Stratonovich transformation is used to
eliminate four quark interactions in vNRQCD and then quarks
and antiquarks are integrated out to get effective
Lagrangians for composite fields. This method is used to
rederive Lagrangians for the Q\bar Q and QQ sectors of
pNRQCD and give a correct derivation of the O(1/m_Q)
prediction for the hyperfine splitting of doubly heavy
baryons.},
Key = {fds43963}
}
@article{fds287638,
Author = {Fleming, S and Mehen, T},
Title = {Doubly heavy baryons, heavy quark-diquark symmetry, and
nonrelativistic QCD},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {73},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2006},
Month = {February},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.73.034502},
Abstract = {In the heavy quark limit, properties of heavy mesons and
doubly heavy baryons are related by heavy quark-diquark
symmetry. This problem is reanalyzed in the framework of
nonrelativistic QCD (NRQCD). We introduce a novel method for
deriving potential NRQCD (pNRQCD) Lagrangians for composite
fields from vNRQCD, which contains quarks and antiquarks as
explicit degrees of freedom and maintains manifest power
counting in the velocity via a label formalism. A
Hubbard-Stratonovich transformation is used to eliminate
four quark interactions in vNRQCD and then quarks and
antiquarks are integrated out to get effective Lagrangians
for composite fields. This method is used to rederive
Lagrangians for the QQ̄ and QQ sectors of pNRQCD and give a
correct derivation of the O(1/mQ) prediction for the
hyperfine splitting of doubly heavy baryons. © 2006 The
American Physical Society.},
Doi = {10.1103/PhysRevD.73.034502},
Key = {fds287638}
}
@article{fds327375,
Author = {Yao, X and Mehen, T and Müller, B},
Title = {Dynamical screening of α-α Resonant scattering and thermal
nuclear scattering rate in a plasma},
Journal = {Physical Review D},
Volume = {95},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2017},
Month = {June},
url = {http://dx.doi.org/10.1103/PhysRevD.95.116002},
Abstract = {We use effective field theory and thermal field theory to
study the dynamical screening effect in the QED plasma on
the α-α scattering at the Be8 resonance. Dynamical
screening leads to an imaginary part of the potential which
results in a thermal width for the resonance and dominates
over the previously considered static screening effect. As a
result, both the resonance energy and width increase with
the plasma temperature. Furthermore, dynamical screening can
have a huge impact on the α-α thermal nuclear scattering
rate. For example, when the temperature is around 10 keV,
the rate is suppressed by a factor of about 900. We expect
similar thermal suppressions of nuclear reaction rates to
occur in those reactions dominated by an above threshold
resonance with a thermal energy. Dynamical screening effects
on nuclear reactions can be relevant to cosmology and
astrophysics.},
Doi = {10.1103/PhysRevD.95.116002},
Key = {fds327375}
}
@article{fds287657,
Author = {Idilbi, A and Mehen, T},
Title = {Equivalence of soft and zero-bin subtractions at two
loops},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {76},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2007},
Month = {November},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/0707.1101},
Abstract = {Calculations of collinear correlation functions in
perturbative QCD and soft-collinear effective theory require
a prescription for subtracting soft or zero-bin
contributions in order to avoid double counting the
contributions from soft modes. At leading order in λ, where
λ is the soft-collinear effective theory expansion
parameter, the zero-bin subtractions have been argued to be
equivalent to convolution with soft Wilson lines. We give a
proof of the factorization of naive collinear Wilson lines
that is crucial for the derivation of the equivalence. We
then check the equivalence by computing the non-Abelian
two-loop mixed collinear-soft contribution to the jet
function in the quark form factor. These results demonstrate
the equivalence, which can be used to give a nonperturbative
definition of the zero-bin subtraction at lowest order in
λ. © 2007 The American Physical Society.},
Doi = {10.1103/PhysRevD.76.094015},
Key = {fds287657}
}
@article{fds305719,
Author = {Mehen, T and Springer, RP},
Title = {Even- and odd-parity charmed meson masses in heavy hadron
chiral perturbation theory},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {72},
Number = {3},
Pages = {1-12},
Publisher = {American Physical Society (APS)},
Year = {2005},
Month = {August},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.72.034006},
Abstract = {We derive mass formulas for the ground state, JP=0- and 1-,
and first excited even-parity, JP=0+ and 1+, charmed mesons
including one-loop chiral corrections and O(1/mc)
counterterms in heavy hadron chiral perturbation theory. We
show that including these counterterms is critical for
fitting the current data. We find that certain parameter
relations in the parity doubling model are not renormalized
at one-loop, providing a natural explanation for the
observed equality of the hyperfine splittings of ground
state and excited doublets. © 2005 The American Physical
Society.},
Doi = {10.1103/PhysRevD.72.034006},
Key = {fds305719}
}
@article{fds287668,
Author = {Mehen, T and Springer, RP},
Title = {Even- and Odd-Parity Charmed Meson Masses in Heavy Hadron
Chiral Perturbation Theory},
Journal = {Phys Rev D},
Volume = {72},
Number = {034006},
Pages = {1-12},
Year = {2005},
Month = {March},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/hep-ph/0503134},
Abstract = {We derive mass formulas for the ground state, JP=0- and 1-,
and first excited even-parity, JP=0+ and 1+, charmed mesons
including one-loop chiral corrections and O(1/mc)
counterterms in heavy hadron chiral perturbation theory. We
show that including these counterterms is critical for
fitting the current data. We find that certain parameter
relations in the parity doubling model are not renormalized
at one-loop, providing a natural explanation for the
observed equality of the hyperfine splittings of ground
state and excited doublets. © 2005 The American Physical
Society.},
Doi = {10.1103/PhysRevD.72.034006},
Key = {fds287668}
}
@article{fds287669,
Author = {Mehen, T},
Title = {Excited Ds (and pentaquarks) in chiral
perturbation theory},
Journal = {Acta Physica Polonica B},
Volume = {36},
Number = {7},
Pages = {2341-2350},
Year = {2005},
Month = {July},
ISSN = {0587-4254},
url = {http://arxiv.org/abs/hep-ph/0506219},
Abstract = {I present results of a heavy hadron chiral perturbation
theory analysis of the decays and masses of the recently
discovered excited charm mesons. The present data on the
electromagnetic branching ratios are consistent with heavy
quark symmetry predictions and disfavor a molecular
interpretation of these states. I also discuss model
independent predictions for the strong decays of pentaquarks
in the 10̄ representation of SU(3) which can be used to
constrain the angular momentum and parity quantum numbers of
these states.},
Key = {fds287669}
}
@booklet{Falk96,
Author = {Falk, AF and Mehen, T},
Title = {Excited heavy mesons beyond leading order in the heavy quark
expansion.},
Journal = {Physical review. D, Particles and fields},
Volume = {53},
Number = {1},
Pages = {231-240},
Publisher = {American Physical Society (APS)},
Year = {1996},
Month = {January},
url = {http://dx.doi.org/10.1103/physrevd.53.231},
Abstract = {We examine the decays of excited heavy mesons, including the
leading power corrections to the heavy quark limit. We find
a anew and natural explanation for the large deviation of
the width of the D1(2420) from the heavy quark symmetry
prediction. Our formalism leads to detailed predictions for
the properties of the excited bottom mesons, some of which
recently have been observed. Finally, we present a detailed
analysis of the effect of power corrections and finite meson
widths on the angular distributions which may be measured in
heavy meson decays. © 1995 The American Physical
Society.},
Doi = {10.1103/physrevd.53.231},
Key = {Falk96}
}
@article{fds287652,
Author = {Idilbi, A and Kim, C and Mehen, T},
Title = {Factorization and resummation for single color-octet scalar
production at the LHC},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {79},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2009},
Month = {June},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/0903.3668},
Abstract = {Heavy colored scalar particles appear in a variety of new
physics (NP) models and could be produced at the Large
Hadron Collider. Knowing the total production cross section
is important for searching for these states and establishing
bounds on their masses and couplings. Using soft-collinear
effective theory, we derive a factorization theorem for the
process pp→SX, where S is a color-octet scalar, that is
applicable to any NP model provided the dominant production
mechanism is gluon-gluon fusion. The factorized result for
the inclusive cross section is similar to that for the
standard model Higgs production; however, differences arise
due to color exchange between initial and final states. We
provide formulas for the total cross section with large
(partonic) threshold logarithms resummed to next-to-leading
logarithm accuracy. The resulting K factors are similar to
those found in Higgs production. We apply our formalism to
the Manohar-Wise model and find that the next-to-leading
logarithm cross section is roughly 2 times (3 times) as
large as the leading order cross section for a color-octet
scalar of mass of 500 GeV (3 TeV). A similar enhancement
should appear in any NP model with color-octet scalars. ©
2009 The American Physical Society.},
Doi = {10.1103/PhysRevD.79.114016},
Key = {fds287652}
}
@article{fds354149,
Author = {Yao, X and Ke, W and Xu, Y and Bass, S and Mehen, T and Müller,
B},
Title = {Fate of heavy quark bound states inside quark-gluon
plasma},
Journal = {Hadron Spectroscopy and Structure},
Publisher = {WORLD SCIENTIFIC},
Year = {2020},
Month = {August},
url = {https://arxiv.org/abs/1912.01633},
Abstract = {Transport equations have been applied successfully to
describe the quarkonium evolution inside the quark-gluon
plasma, which include both plasma screening effects and
recombination. We demonstrate how the quarkonium transport
equation is derived from QCD by using the open quantum
system framework and effective field theory. Weak coupling
and Markovian approximations used in the derivation are
justified from a separation of scales. By solving the
equations numerically, we study the Upsilon production in
heavy ion collisions.},
Doi = {10.1142/9789811219313_0118},
Key = {fds354149}
}
@article{fds338043,
Author = {Kang, D and Makris, Y and Mehen, T},
Title = {From underlying event sensitive to insensitive:
factorization and resummation},
Journal = {Journal of High Energy Physics},
Volume = {2018},
Number = {9},
Publisher = {Springer Nature America, Inc},
Year = {2018},
Month = {September},
url = {http://dx.doi.org/10.1007/JHEP09(2018)055},
Abstract = {In this paper we study the transverse energy spectrum for
the Drell-Yan process. The transverse energy is measured
within the central region defined by a (pseudo-) rapidity
cutoff. Soft-collinear effective theory (SCET) is used to
factorize the cross section and resum large logarithms of
the rapidity cutoff and ratios of widely separated scales
that appear in the fixed order result. We develop a
framework which can smoothly interpolate between various
regions of the spectrum and eventually match onto the fixed
order result. This way a reliable calculation is obtained
for the contribution of the initial state radiation to the
measurement. By comparing our result for Drell-Yan against
Pythia we obtain a simple model that describes the
contribution from multiparton interactions (MPI). A model
with little or no dependence on the primary process gives
results in agreement with the simulation. Based on this
observation we propose MPI insensitive measurements. These
observables are insensitive to the MPI contributions as
implemented in Pythia and we compare against the purely
perturbative result obtained with the standard collinear
factorization.},
Doi = {10.1007/JHEP09(2018)055},
Key = {fds338043}
}
@article{fds305718,
Author = {Mehen, T and Wecht, B},
Title = {Gauge fields and scalars in rolling tachyon
backgrounds},
Journal = {Journal of High Energy Physics},
Volume = {7},
Number = {2},
Pages = {1313-1326},
Year = {2003},
Month = {February},
url = {http://dx.doi.org/10.1088/1126-6708/2003/02/058},
Abstract = {We investigate the dynamics of gauge and scalar fields on
unstable D-branes with rolling tachyons. Assuming an FRW
metric on the brane, we find a solution of the tachyon
equation of motion which is valid for arbitrary tachyon
potentials and scale factors. The equations of motion for a
U(1) gauge field and a scalar field in this background are
derived. These fields see an effective metric which differs
from the original FRW metric. The field equations receive
large corrections due to the curvature of the effective
metric as well as the time variation of the gauge coupling.
The equations of state for these fields resemble those of
nonrelativistic matter rather than those of massless
particles. © SISSA/ISAS 2003.},
Doi = {10.1088/1126-6708/2003/02/058},
Key = {fds305718}
}
@article{fds287672,
Author = {Mehen, T and Wecht, B},
Title = {Gauge Fields and Scalars in Rolling Tachyon
Backgrounds},
Journal = {JHEP 0302},
Volume = {7},
Number = {2},
Pages = {58},
Year = {2003},
url = {http://arxiv.org/abs/hep-th/0206212},
Abstract = {We investigate the dynamics of gauge and scalar fields on
unstable D-branes with rolling tachyons. Assuming an FRW
metric on the brane, we find a solution of the tachyon
equation of motion which is valid for arbitrary tachyon
potentials and scale factors. The equations of motion for a
U(1) gauge field and a scalar field in this background are
derived. These fields see an effective metric which differs
from the original FRW metric. The field equations receive
large corrections due to the curvature of the effective
metric as well as the time variation of the gauge coupling.
The equations of state for these fields resemble those of
nonrelativistic matter rather than massless
particles.},
Key = {fds287672}
}
@article{fds287691,
Author = {Mehen, T and Wise, MB},
Title = {Generalized *-Products, Wilson Lines and the Solution of the
Seiberg-Witten Equations},
Journal = {JHEP},
Volume = {12},
Number = {12},
Pages = {8},
Year = {2000},
url = {http://dx.doi.org/10.1088/1126-6708/2000/12/008},
Abstract = {Higher order terms in the effective action of noncommutative
gauge theories exhibit generalizations of the *-product
(e.g. *' and *-3). These terms do not manifestly respect the
noncommutative gauge invariance of the tree level action. In
U(1) gauge theories, we note that these generalized
*-products occur in the expansion of some quantities that
are invariant under noncommutative gauge transformations,
but contain an infinite number of powers of the
noncommutative gauge field. One example is an open Wilson
line. Another is the expression for a commutative field
strength tensor in terms of the noncommutative gauge field.
Seiberg and Witten derived differential equations that
relate commutative and noncommutative gauge transformations,
gauge fields and field strengths. In the U(1) case we solve
these equations neglecting terms of fourth order in the
gauge field but keeping all orders in the noncommutative
parameter.},
Doi = {10.1088/1126-6708/2000/12/008},
Key = {fds287691}
}
@article{fds305715,
Author = {Mehen, T and Wise, MB},
Title = {Generalized *-products, Wilson lines and the solution of the
Seiberg-Witten equations},
Journal = {Journal of High Energy Physics},
Volume = {4},
Number = {12},
Pages = {XVII-9},
Year = {2000},
Abstract = {Higher order terms in the effective action of
non-commutative gauge theories exhibit generalizations of
the *-product (e.g. *′ and *3). These terms do not
manifestly respect the non-commutative gauge invariance of
the tree level action. In U(1) gauge theories, we note that
these generalized *-products occur in the expansion of some
quantities that are invariant under non-commutative gauge
transformations, but contain an infinite number of powers of
the non-commutative gauge field. One example is an open
Wilson line. Another is the expression for a commutative
field strength tensor Fab in terms of the non-commutative
gauge field Âa. Seiberg and Witten derived differential
equations that relate commutative and non-commutative gauge
transformations, gauge fields and field strengths. In the
U(1) case we solve these equations neglecting terms of
fourth order in  but keeping all orders in the
non-commutative parameter θkl.},
Key = {fds305715}
}
@article{fds287654,
Author = {Fleming, S and Mehen, T},
Title = {Hadronic decays of the X(3872) to χcJ in effective field
theory},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {78},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2008},
Month = {November},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/0807.2674v2},
Abstract = {The decays of the X(3872) to P-wave quarkonia are calculated
under the assumption that it is a shallow bound state of
neutral charmed mesons. The X(3872) is described using an
effective theory of nonrelativistic D mesons and pions
(X-EFT). We calculate X(3872) decays by first matching heavy
hadron chiral perturbation theory (HHχPT) amplitudes for
D0D̄ *0→χcJ(π0,ππ) onto local operators in X-EFT, and
then using these operators to calculate the X(3872) decays.
This procedure reproduces the factorization theorems for
X(3872) decays to conventional quarkonia previously derived
using the operator product expansion. For single pion
decays, we find nontrivial dependence on the pion energy
from HHχPT diagrams with virtual D mesons. This nontrivial
energy dependence can potentially modify heavy-quark
symmetry predictions for the relative sizes of decay rates.
At leading order, decays to final states with two pions are
dominated by the final state χc1π0π0, with a branching
fraction just below that for the decay to χc1π0. Decays to
all other final states with two pions are highly suppressed.
© 2008 The American Physical Society.},
Doi = {10.1103/PhysRevD.78.094019},
Key = {fds287654}
}
@article{fds287615,
Author = {Mehen, T},
Title = {Hadronic loops versus factorization in effective field
theory calculations of X (3872) →χcJπ0},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {92},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2015},
Month = {August},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.92.034019},
Abstract = {We compare two existing approaches to calculating the decay
of molecular quarkonium states to conventional quarkonia in
effective field theory, using X(3872)→χcJπ0 as an
example. In one approach the decay of the molecular
quarkonium proceeds through a triangle diagram with charmed
mesons in the loop. We argue this approach predicts
excessively large rates for Γ[X(3872)→χcJπ0] unless
both charged and neutral mesons are included and a
cancellation between these contributions is arranged to
suppress the decay rates. This cancellation occurs naturally
if the X(3872) is primarily in the I=0 DD¯∗+c.c
scattering channel. The factorization approach to molecular
decays calculates the rates in terms of tree-level
transitions for the D mesons in the X(3872) to the final
state, multiplied by unknown matrix elements. We show that
this approach is equivalent to the hadronic loops approach
if the cutoff on the loop integrations is taken to be a few
hundred MeV or smaller, as is appropriate when the charged D
mesons have been integrated out of the effective
theory.},
Doi = {10.1103/PhysRevD.92.034019},
Key = {fds287615}
}
@article{fds287644,
Author = {Mehen, T and Powell, JW},
Title = {Heavy quark symmetry predictions for weakly bound B-meson
molecules},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {84},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {December},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/1109.3479},
Abstract = {Recently the Belle collaboration discovered two resonances,
Z b(10610) and Z b(10650), that lie very close to the BB ̄*
and B *B ̄* thresholds, respectively. It is natural to
suppose that these are molecular states of bottom and
antibottom mesons. Under this assumption, we introduce an
effective field theory for the Z b(10610) and Z b(10650), as
well as similar unobserved states that are expected on the
basis of heavy quark spin symmetry. The molecules are
assumed to arise from short-range interactions that respect
heavy quark spin symmetry. We use the theory to calculate
line shapes in the vicinity of B( *)B ̄(*) thresholds as
well as two-body decay rates of the new bottom meson bound
states. We derive new heavy quark spin symmetry predictions
for the parameters appearing in the line shapes as well as
the total and partial widths of the states. © 2011 American
Physical Society.},
Doi = {10.1103/PhysRevD.84.114013},
Key = {fds287644}
}
@article{fds287617,
Author = {Mehen, T},
Title = {Heavy quark-diquark symmetry and &ChiPT for doubly heavy
baryons},
Journal = {Chiral Dynamics 2006 - Proceedings of the 5th International
Workshop on Chiral Dynamics, Theory and Experiment, CD
2006},
Pages = {299-301},
Year = {2007},
Month = {December},
Abstract = {A chiral Lagrangian incorporating heavy quark-diquark
symmetry is used to calculate doubly charm baryon
electromagnetic decays and chiral corrections to doubly
heavy baryon masses. Quenched and partially quenched
versions of the theory allow one to derive chiral
extrapolation formulae for lattice QCD simulations of doubly
heavy baryons.},
Key = {fds287617}
}
@article{fds287620,
Author = {Mehen, T},
Title = {Heavy quark-diquark symmetry and X PT for Doubly Heavy
Baryons},
Journal = {Annual Meeting of the Division of Particles and Fields of
the American Physical Society, DPF 2006, and the Annual Fall
Meeting of the Japan Particle Physics Community},
Pages = {299-301},
Year = {2006},
Month = {January},
Abstract = {A chiral Lagrangian incorporating heavy quark-diquark
symmetry is used to calculate doubly charm baryon
electromagnetic decays and chiral corrections to doubly
heavy baryon masses. Quenched and partially quenched
versions of the theory allow one to derive chiral
extrapolation formulae for lattice QCD simulations of doubly
heavy baryons.},
Key = {fds287620}
}
@article{fds29799,
Author = {T. Mehen and R. P. Springer},
Title = {Heavy-Quark Symmetry and the Electromagnetic Decays of
Excited Charm Strange Mesons},
Journal = {Phys. Rev. D70, 074014},
Year = {2004},
url = {http://arxiv.org/abs/hep-ph/0407181},
Abstract = {Heavy-hadron chiral perturbation theory (HH$\chi$PT) is
applied to the decays of the even-parity charmed strange
mesons, D_{s0}(2317) and D_{s1}(2460). Heavy-quark spin
symmetry predicts the branching fractions for the three
electromagnetic decays of these states to the ground states
D_s and D_s^* in terms of a single parameter. The resulting
predictions for two of the branching fractions are
significantly higher than current upper limits from the CLEO
experiment. Leading corrections to the branching ratios from
chiral loop diagrams and spin-symmetry violating operators
in the HH$\chi$PT Lagrangian can naturally account for this
discrepancy. Finally the proposal that the D_{s0}(2317)
(D_{s1}(2460)) is a hadronic bound state of a D (D^*) meson
and a kaon is considered. Leading order predictions for
electromagnetic branching ratios in this molecular scenario
are in very poor agreement with existing
data.},
Key = {fds29799}
}
@article{fds287613,
Author = {Mehen, T and Springer, RP},
Title = {Heavy-quark symmetry and the electromagnetic decays of
excited charmed strange mesons},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {70},
Number = {7},
Pages = {074014-1-074014-12},
Year = {2004},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.70.074014},
Abstract = {Heavy-hadron chiral perturbation theory (HHχPT) is applied
to the decays of the even-parity charmed strange mesons,
Ds0(2317) and Ds1(2460). Heavy-quark spin-symmetry predicts
the branching fractions for the three electromagnetic decays
of these states to the ground states Ds and Ds* in terms of
a single parameter. The resulting predictions for two of the
branching fractions are significantly higher than current
upper limits from the CLEO experiment. Leading corrections
to the branching ratios from chiral loop diagrams and
spin-symmetry violating operators in the HHχPT Lagrangian
can naturally account for this discrepancy. Finally the
proposal that the Ds0(2317) (D s1(2460)) is a hadronic bound
state of a D(D*) meson and a kaon is considered. Leading
order predictions for electromagnetic branching ratios in
this molecular scenario are in very poor agreement with
existing data.},
Doi = {10.1103/PhysRevD.70.074014},
Key = {fds287613}
}
@article{fds331488,
Author = {Mehen, T},
Title = {Implications of heavy quark-diquark symmetry for excited
doubly heavy baryons and tetraquarks},
Journal = {Physical Review D},
Volume = {96},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2017},
Month = {November},
url = {http://dx.doi.org/10.1103/PhysRevD.96.094028},
Abstract = {We give heavy quark-diquark symmetry predictions for doubly
heavy baryons and tetraquarks in light of the recent
discovery of the Ξcc++ by LHCb. For five excited doubly
charm baryons that are predicted to lie below the ΛcD
threshold, we give predictions for their electromagnetic and
strong decays using a previously developed chiral Lagrangian
with heavy quark-diquark symmetry. Based on the mass of the
Ξcc++, the existence of a doubly heavy bottom I=0
tetraquark that is stable to strong and electromagnetic
decays has been predicted. If the mass of this state is
below 10405 MeV, as predicted in some models, we argue using
heavy quark-diquark symmetry that the JP=1+ I=1 doubly
bottom tetraquark state will lie just below the open bottom
threshold and likely be a narrow state as well. In this
scenario, we compute strong decay width for this state using
a new Lagrangian for doubly heavy tetraquarks which is
related to the singly heavy baryon Lagrangian by heavy
quark-diquark symmetry.},
Doi = {10.1103/PhysRevD.96.094028},
Key = {fds331488}
}
@article{fds340921,
Author = {Kaiser, R and Manohar, AV and Mehen, T},
Title = {Isospin violation in e+ e- -->BB.},
Journal = {Physical review letters},
Volume = {90},
Number = {14},
Pages = {142001},
Year = {2003},
Month = {April},
url = {http://dx.doi.org/10.1103/physrevlett.90.142001},
Abstract = {The ratio of the B+ B- and B0B0 production rates in e+ e-
annihilation is computed as a function of the B meson
velocity and BB*pi coupling constant, using a
nonrelativistic effective field theory.},
Doi = {10.1103/physrevlett.90.142001},
Key = {fds340921}
}
@article{fds287633,
Author = {Kaiser, R and Manohar, AV and Mehen, T},
Title = {Isospin violation in e+e- →
BB̄},
Journal = {Physical Review Letters},
Volume = {90},
Number = {14},
Pages = {142001/1-142001/4},
Year = {2003},
Month = {April},
url = {http://arxiv.org/abs/hep-ph/0208194},
Abstract = {An overview is given of the computation of R+/0. The result
depends on two parameters: the Β*Βπ coupling and δc,
which represents the isospin violating part of the Y(4S)
coupling to Β̄Β states.},
Doi = {10.1103/PhysRevLett.90.142001},
Key = {fds287633}
}
@article{fds287616,
Author = {Leibovich, A and Fleming, S and Mehen, T},
Title = {J/φ photoproduction at the endpoint},
Journal = {Annual Meeting of the Division of Particles and Fields of
the American Physical Society, DPF 2006, and the Annual Fall
Meeting of the Japan Particle Physics Community},
Year = {2006},
Month = {January},
Key = {fds287616}
}
@article{fds287619,
Author = {Fleming, S and Leibovich, AK and Mehen, T},
Title = {J/Ψ photo-production at large z in soft collinear effective
theory},
Journal = {Proceedings of the Ringberg Workshop on New Trends in HERA
Physics 2005},
Pages = {239-250},
Year = {2006},
Month = {January},
url = {http://arxiv.org/abs/hep-ph/0512194},
Abstract = {One of the outstanding problems in J/Ψ physics is a
systematic understanding of the differential
photo-production cross section dσ/dz(γ+p → J/Ψ + X),
where z = EΨ,/E gamma;/ in the proton rest frame. The
theoretical prediction based on the nonrelativistic QCD
(NRQCD) factorization formalism has a color-octet
contribution which grows rapidly in the endpoint region, z
-→ 1, spoiling perturbation theory. In addition there are
subleading operators which are enhanced by powers of 1/(1 -
z) and they must be resummed to all orders. Here an update
of a systematic analysis is presented. The approach used to
organize the endpoint behavior of the photoproduction cross
section is based on a combination of NRQCD and soft
collinear effective theory. While a final result is not yet
available, an intermediate result indicates that better
agreement between theory and data will be achieved in this
framework. Copyright © 2006 by World Scientific Publishing
Co. Pte. Ltd.},
Doi = {10.1142/9789812773524_0022},
Key = {fds287619}
}
@article{fds322011,
Author = {Hornig, A and Makris, Y and Mehen, T},
Title = {Jet shapes in dijet events at the LHC in
SCET},
Journal = {Journal of High Energy Physics},
Volume = {2016},
Number = {4},
Pages = {1-41},
Publisher = {Springer Nature},
Year = {2016},
Month = {April},
url = {http://dx.doi.org/10.1007/JHEP04(2016)097},
Abstract = {Abstract: We consider the class of jet shapes known as
angularities in dijet production at hadron colliders. These
angularities are modified from the original definitions in
e+e− collisions to be boost invariant along the beam axis.
These shapes apply to the constituents of jets defined with
respect to either kT-type (anti-kT, C/A, and kT) algorithms
and cone-type algorithms. We present an SCET factorization
formula and calculate the ingredients needed to achieve
next-to-leading-log (NLL) accuracy in kinematic regions
where non-global logarithms are not large. The factorization
formula involves previously unstudied “unmeasured beam
functions,” which are present for finite rapidity cuts
around the beams. We derive relations between the jet
functions and the shape-dependent part of the soft function
that appear in the factorized cross section and those
previously calculated for e+e− collisions, and present the
calculation of the non-trivial, color-connected part of the
soft-function to (Formula presented.). This latter part of
the soft function is universal in the sense that it applies
to any experimental setup with an out-of-jet pT veto and
rapidity cuts together with two identified jets and it is
independent of the choice of jet (sub-)structure
measurement. In addition, we implement the recently
introduced soft-collinear refactorization to resum
logarithms of the jet size, valid in the region of
non-enhanced non-global logarithm effects. While our results
are valid for all 2 → 2 channels, we compute explicitly
for the qq′ → qq′ channel the color-flow matrices and
plot the NLL resummed differential dijet cross section as an
explicit example, which shows that the normalization and
scale uncertainty is reduced when the soft function is
refactorized. For this channel, we also plot the jet size R
dependence, the pTcut dependence, and the dependence on the
angularity parameter a.},
Doi = {10.1007/JHEP04(2016)097},
Key = {fds322011}
}
@article{fds287632,
Author = {Braaten, E and Jia, Y and Mehen, T},
Title = {Leading-particle effect from heavy-quark
recombination.},
Journal = {Physical review letters},
Volume = {89},
Number = {12},
Pages = {122002},
Publisher = {American Physical Society (APS)},
Year = {2002},
Month = {September},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/physrevlett.89.122002},
Abstract = {The leading particle effect in charm hadroproduction is an
enhancement of the cross section for a charmed hadron D in
the forward direction of the beam when the beam hadron has a
valence parton in common with the D. The large D(+)/D(-)
asymmetry observed by the E791 experiment is an example of
this phenomenon. We show that the heavy-quark recombination
mechanism provides an economical expla-nation for this
effect. In particular, the D(+)/D(-) asymmetry can be fit
reasonably well using a single parameter whose value is
consistent with a recent determination from charm
photoproduction.},
Doi = {10.1103/physrevlett.89.122002},
Key = {fds287632}
}
@article{fds3910,
Author = {T. Mehen},
Title = {Leptoproduction of $J/\Psi$},
Booktitle = {Proceedings of the 29th International Conference on High
Energy Physics (ICHEP 98)},
Publisher = {World Scientific},
Editor = {A. Astbury and D. Axen and J. Robinson},
Year = {1999},
Abstract = {I review the status of the extraction of NRQCD color-octet
$J/\psi$ production matrix elements. Large theoretical
uncertainties in current extractions from hadroproduction
and photoproduction are emphasized. Leptoproduction of
$J/\psi$ is calculated within the NRQCD factorization
formalism. Color-octet contributions dominate the cross
section, allowing for a reliable extraction of $<{\cal
O}_8^{J/\psi}(^1S_0)>$ and $<{\cal O}_8^{J/\psi}(^3P_0)>$. A
comparison with preliminary data from the H1 collaboration
shows that leading order color-octet mechanisms agree with
the measured total cross section for $Q^2 > 4m_c^2$, while
the color-singlet model underpredicts the cross section by a
factor of 5.},
Key = {fds3910}
}
@booklet{Fleming98a,
Author = {Fleming, S},
Title = {Leptoproduction of [Formula presented]},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {57},
Number = {3},
Pages = {1846-1857},
Publisher = {American Physical Society (APS)},
Year = {1998},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevD.57.1846},
Abstract = {We study leptoproduction of (Formula presented) at large
(Formula presented) within the nonrelativistic QCD (NRQCD)
factorization formalism. The cross section is dominated by
color-octet terms that are of order (Formula presented) The
color-singlet term, which is of order (Formula presented),
is shown to make a small contribution to the total cross
section. We also calculate the tree diagrams for color-octet
production at order (Formula presented) in a region of phase
space where there is no leading color-octet contribution. We
find that in this regime the color-singlet contribution
dominates. We argue that nonperturbative corrections arising
from diffractive leptoproduction, higher twist effects, and
higher order terms in the NRQCD velocity expansion should be
suppressed as (Formula presented) is increased. Therefore,
the color-octet matrix elements (Formula presented) and
(Formula presented) can be reliably extracted from this
process. Finally, we point out that an experimental
measurement of the polarization of leptoproduced (Formula
presented) will provide an excellent test of the NRQCD
factorization formalism. © 1998 The American Physical
Society.},
Doi = {10.1103/PhysRevD.57.1846},
Key = {Fleming98a}
}
@article{fds287621,
Author = {Mehen, T and Powell, JW},
Title = {Line shapes in Υ(5S)→B(*)B
̄(*)π with Z(10610) and Z(10650)
using effective field theory},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {88},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2013},
Month = {August},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.88.034017},
Abstract = {The Belle Collaboration recently discovered two resonances,
Z b(10610) and Zb(10650) - denoted Zb and Zb′ - in the
decays Υ(5S)→Υ(nS)π+π - for n=1, 2, or 3, and
Υ(5S)→hb(mP) π+π- for m=1 or 2. These resonances lie
very close to the B*B̄ and B*B̄* thresholds, respectively.
A recent Belle analysis of the three-body decays
Υ(5S)→[B(*)B̄( *)]â̂π± gives further evidence for
the existence of these states. In this paper we analyze this
decay using an effective theory of B mesons interacting via
strong short-range interactions. Some parameters in this
theory are constrained using existing data on
Υ(5S)→B(*)B̄( *) decays, which requires the inclusion of
heavy quark spin symmetry violating operators. We then
calculate the differential distribution for
Υ(5S)→B(*)B̄(*) π as a function of the invariant mass
of the B(*)B ̄(*) pair, obtaining qualitative agreement
with experimental data. We also calculate angular
distributions in the decay Υ(5S)→Zb(′)π which are
sensitive to the molecular character of the Zb(′). © 2013
American Physical Society.},
Doi = {10.1103/PhysRevD.88.034017},
Key = {fds287621}
}
@article{fds221123,
Author = {Thomas Mehen and Joshua W. Powell},
Title = {Line shapes in Υ(5S)→B(∗) B(∗)π
with Z(10610) and Z(10650) using effective field
theory},
Journal = {Phys. Rev. D88:034017},
Year = {2013},
url = {http://arxiv.org/abs/1306.5459},
Key = {fds221123}
}
@article{fds369694,
Author = {Liu, Q and Low, I and Mehen, T},
Title = {Minimal entanglement and emergent symmetries in low-energy
QCD},
Journal = {Physical Review C},
Volume = {107},
Number = {2},
Publisher = {American Physical Society (APS)},
Year = {2023},
Month = {February},
url = {http://dx.doi.org/10.1103/PhysRevC.107.025204},
Abstract = {We study low-energy scattering of spin-12 baryons from the
perspective of quantum information science, focusing on the
correlation between entanglement minimization and the
appearance of accidental symmetries. The baryon transforms
as an octet under the SU(3) flavor symmetry and its
interactions below the pion threshold are described by
contact operators in an effective field theory (EFT) of QCD.
Despite there being 64 channels in the 2-to-2 scattering,
only six independent operators in the EFT are predicted by
SU(3). We show that successive entanglement minimization in
SU(3)-symmetric channels are correlated with increasingly
large emergent symmetries in the EFT. In particular, we
identify scattering channels whose entanglement suppression
are indicative of emergent SU(6), SO(8), SU(8), and SU(16)
symmetries. We also observe the appearance of
non-relativistic conformal invariance in channels with
unnaturally large scattering lengths. Improved precision
from lattice simulations could help determine the degree of
entanglement suppression, and consequently the amount of
accidental symmetry, in low-energy QCD.},
Doi = {10.1103/PhysRevC.107.025204},
Key = {fds369694}
}
@article{fds322012,
Author = {Mehen, T},
Title = {New tests of NRQCD from Quarkonia within
jets},
Journal = {Proceedings of Science},
Volume = {26-30-May-2015},
Year = {2015},
Month = {January},
Abstract = {I review the current status of quarkonium production theory
based on the non-relativistic QCD factorization formalism
(NRQCD). While this theory describes much of the world's
data on J=y and ¡ production, there are still outstanding
problems, most notably the polarization of quarkonia at
large pT in hadron colliders. In this talk we will present
new tests of NRQCD involving the distribution of quarkonia
within jets. The distribution of hadrons within jets is
determined by nonperturbative functions called fragmenting
jet functions (FJFs). FJFs are convolutions of fragmentation
functions, evolved to the jet energy scale, with
perturbatively calculable matching coefficients. I show how
the FJFs for quarkonia can be calculated in NRQCD in terms
of a few NRQCD long-distance matrix elements (LDME), so the
dependence of the cross section on the energy fraction of
the heavy quarkonium, z, is sensitive to the underlying
production mechanism, and therefore provides a new test of
NRQCD. The jet energy and z dependence of the cross section
can be used to perform an independent extraction of NRQCD
LDME. Finally, I describe ongoing work building on this
result. This includes comparison of analytic resummed
calculations with Monte Carlo simulations for two-jet events
in e+e- collisions with B mesons, and three-jet events with
J=y, as well as the definition of boost invariant jet
substructure variables and calculation of a boost invariant
soft function that are necessary for analytic calculations
of jet cross sections at the Large Hadron Collider.
QCD.},
Key = {fds322012}
}
@article{fds322013,
Author = {Fleming, S and Mehen, T and Stewart, IW},
Title = {NN scattering 3S1-3D1
mixing angle at next-to-next-to-leading order},
Journal = {Physical Review C - Nuclear Physics},
Volume = {61},
Number = {4},
Pages = {440051-440059},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevC.61.044005},
Abstract = {The 3S1-3D1 mixing angle for nucleon-nucleon scattering ∈1
is calculated to next-to-next-to-leading order in an
effective field theory with perturbative pions. Without
pions, the low energy theory fits the observed ∈1 well for
momenta less than∼50 MeV. Including pions perturbatively
significantly improves the agreement with data for momenta
up to ∼150 MeV with one less parameter. Furthermore, for
these momenta the accuracy of our calculation is similar to
an effective field theory calculation in which the pion is
treated nonperturbatively. This gives phenomenological
support for a perturbative treatment of pions in low energy
two-nucleon processes. We explain why it is necessary to
perform spin and isospin traces in d dimensions when
regulating divergences with dimensional regularization in
higher partial wave amplitudes.},
Doi = {10.1103/PhysRevC.61.044005},
Key = {fds322013}
}
@article{fds305717,
Author = {Fleming, S and Mehen, T and Stewart, IW},
Title = {NN scattering 3S1-3D1
mixing angle at next-to-next-to-leading order},
Journal = {Physical Review C - Nuclear Physics},
Volume = {61},
Number = {4},
Pages = {440051-440059},
Year = {2000},
url = {http://dx.doi.org/10.1103/PhysRevC.61.044005},
Abstract = {The 3S1-3D1 mixing angle for nucleon-nucleon scattering ∈1
is calculated to next-to-next-to-leading order in an
effective field theory with perturbative pions. Without
pions, the low energy theory fits the observed ∈1 well for
momenta less than∼50 MeV. Including pions perturbatively
significantly improves the agreement with data for momenta
up to ∼150 MeV with one less parameter. Furthermore, for
these momenta the accuracy of our calculation is similar to
an effective field theory calculation in which the pion is
treated nonperturbatively. This gives phenomenological
support for a perturbative treatment of pions in low energy
two-nucleon processes. We explain why it is necessary to
perform spin and isospin traces in d dimensions when
regulating divergences with dimensional regularization in
higher partial wave amplitudes.},
Doi = {10.1103/PhysRevC.61.044005},
Key = {fds305717}
}
@article{fds340922,
Author = {Fleming, S and Mehen, T and Stewart, IW},
Title = {NN scattering [Formula Presented] mixing angle at
next-to-next-to-leading order},
Journal = {Physical Review C - Nuclear Physics},
Volume = {61},
Number = {4},
Pages = {9},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevC.61.044005},
Abstract = {The [Formula Presented] mixing angle for nucleon-nucleon
scattering [Formula Presented] is calculated to
next-to-next-to-leading order in an effective field theory
with perturbative pions. Without pions, the low energy
theory fits the observed [Formula Presented] well for
momenta less than ∼50 MeV. Including pions perturbatively
significantly improves the agreement with data for momenta
up to ∼150 MeV with one less parameter. Furthermore, for
these momenta the accuracy of our calculation is similar to
an effective field theory calculation in which the pion is
treated nonperturbatively. This gives phenomenological
support for a perturbative treatment of pions in low energy
two-nucleon processes. We explain why it is necessary to
perform spin and isospin traces in d dimensions when
regulating divergences with dimensional regularization in
higher partial wave amplitudes. © 2000 The American
Physical Society.},
Doi = {10.1103/PhysRevC.61.044005},
Key = {fds340922}
}
@article{fds287686,
Author = {Fleming, S and Mehen, T and Stewart, IW},
Title = {NNLO corrections to nucleon-nucleon scattering and
perturbative pions},
Journal = {Nuclear Physics A},
Volume = {677},
Number = {1-4},
Pages = {313-366},
Publisher = {Elsevier BV},
Year = {2000},
Month = {September},
url = {http://dx.doi.org/10.1016/S0375-9474(00)00221-9},
Abstract = {The 1S0, 3S1, and 3D1 nucleon-nucleon scattering phase
shifts are calculated at next-to-next-to-leading order
(NNLO) in an effective field theory. Predictions for the
1P1, 3P0,1,2, 1D2, and 3D2,3 phase shifts at this order are
also compared with data. The calculations treat pions
perturbatively and include the NNLO contributions from order
Qr3 and Qr4 radiation pion graphs. In the 3S1, 3D1 and 3P0,2
channels we find large disagreement with the Nijmegen
partial-wave analysis at NNLO. These spin triplet channels
have large corrections from graphs with two potential pion
exchange which do not vanish in the chiral limit. We compare
our results to calculations within the Weinberg approach,
and find that in some spin triplet channels the summation of
potential pion diagrams seems to be necessary to reproduce
the observed phase shifts. In the spin singlet channels the
nonperturbative treatment of potential pions does not afford
a significant improvement over the perturbative approach. ©
2000 Elsevier Science B.V.},
Doi = {10.1016/S0375-9474(00)00221-9},
Key = {fds287686}
}
@article{fds305714,
Author = {Gomis, J and Mehen, T and Rangamani, M and Kleban, M and Shenker,
S},
Title = {Non-commutative gauge dynamics from the string
worldsheet},
Journal = {Journal of High Energy Physics},
Volume = {4},
Number = {8 PART A},
Pages = {1-18},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1088/1126-6708/2000/08/011},
Abstract = {We show how string theory can be used to reproduce the
one-loop two-point photon amplitude in non-commutative U(1)
gauge theory. Using a simple realization of the gauge theory
in bosonic string theory, we extract from a string cylinder
computation in the decoupling limit the exact one loop field
theory result. The result is obtained entirely from the
region of moduli space where massless open strings dominate.
Our computation indicates that the unusual IR/UV
singularities of non-commutative field theory do not come
from closed string modes in any simple way.},
Doi = {10.1088/1126-6708/2000/08/011},
Key = {fds305714}
}
@article{fds287687,
Author = {Gomis, J and Kleban, M and Mehen, T and Rangamani, M and Shenker,
S},
Title = {Noncommutative Gauge Dynamics from the String World
Sheet},
Journal = {JHEP},
Volume = {8},
Number = {8},
Pages = {11},
Year = {2000},
Abstract = {We show how string theory can be used to reproduce the
one-loop two-point photon amplitude in noncommutative U(1)
gauge theory. Using a simple realization of the gauge theory
in bosonic string theory, we extract from a string cylinder
computation in the decoupling limit the exact one loop field
theory result. The result is obtained entirely from the
region of moduli space where massless open strings dominate.
Our computation indicates that the unusual IR/UV
singularities of noncommutative field theory do not come
from closed string modes in any simple way.},
Key = {fds287687}
}
@article{fds287655,
Author = {Kim, C and Leibovich, AK and Mehen, T},
Title = {Nonperturbative charming penguin contributions to isospin
asymmetries in radiative B decays},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {78},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2008},
Month = {September},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/0805.1735},
Abstract = {Recent experimental data on the radiative decays B→Vγ,
where V is a light vector meson, find small isospin
violation in B→K*γ while isospin asymmetries in B→ργ
are of order 20%, with large uncertainties. Using
soft-collinear effective theory, we calculate isospin
asymmetries in these radiative B decays up to O(1/mb), also
including O(vαs) contributions from nonperturbative
charming penguins (NPCP). In the absence of NPCP
contributions, the theoretical predictions for the
asymmetries are a few percent or less. Including the NPCP
can significantly increase the isospin asymmetries for both
B→Vγ modes. We also consider the effect of the NPCP on
the branching ratio and CP asymmetries in B±→ V±γ. ©
2008 The American Physical Society.},
Doi = {10.1103/PhysRevD.78.054024},
Key = {fds287655}
}
@article{fds287639,
Author = {Mehen, T},
Title = {Nonrelativistic conformal field theory and trapped atoms:
Virial theorems and the state-operator correspondence in
three dimensions},
Journal = {Physical Review A - Atomic, Molecular, and Optical
Physics},
Volume = {78},
Number = {1},
Publisher = {American Physical Society (APS)},
Year = {2008},
Month = {July},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.78.013614},
Abstract = {The field theory of nonrelativistic fermions interacting via
contact interactions can be used to calculate the properties
of few-body systems of cold atoms confined in harmonic
traps. The state-operator correspondence of nonrelativistic
conformal field theory (NRCFT) shows that the energy
eigenvalues (in oscillator units) of N harmonically trapped
fermions can be calculated from the scaling dimensions of N
-fermion operators in the NRCFT. They are also in one-to-one
correspondence with zero energy, scale-invariant solutions
to the N -body problem in free space. We show that these two
mappings of the trapped fermion problem to free space
problems are related by an automorphism of the SL (2,R)
algebra of the conformal symmetry of fermions at the unitary
limit. This automorphism exchanges the internal Hamiltonian
of the gas with the trapping potential and hence provides a
method for deriving virial theorems for trapped Fermi gases
at the unitary limit. We also show that the state-operator
correspondence can be applied directly in three spatial
dimensions by calculating the scaling dimensions of two- and
three-fermion operators and finding agreement with known
exact results for energy levels of two and three trapped
fermions at the unitary limit. © 2008 The American Physical
Society.},
Doi = {10.1103/PhysRevA.78.013614},
Key = {fds287639}
}
@article{fds328273,
Author = {Bain, R and Makris, Y and Mehen, T and Dai, L and Leibovich,
AK},
Title = {NRQCD Confronts LHCb Data on Quarkonium Production within
Jets.},
Journal = {Physical review letters},
Volume = {119},
Number = {3},
Pages = {032002},
Year = {2017},
Month = {July},
url = {http://dx.doi.org/10.1103/physrevlett.119.032002},
Abstract = {We analyze the recent LHCb measurement of the distribution
of the fraction of the transverse momentum, z(J/ψ), carried
by the J/ψ within a jet. LHCb data are compared with
analytic calculations using the fragmenting jet function
(FJF) formalism for studying J/ψ in jets. Logarithms in the
FJFs are resummed using Dokshitzer-Gribov-Lipatov-Altarelli-Parisi
evolution. We also convolve hard QCD partonic cross
sections, showered with pythia, with leading order
nonrelativistic quantum chromodynamics (NRQCD) fragmentation
functions and obtain consistent results. Both approaches use
madgraph to calculate the hard process that creates the jet
initiating parton. These calculations give reasonable
agreement with the z(J/ψ) distribution that was shown to be
poorly described by default pythia simulations in the LHCb
paper. We compare our predictions for the J/ψ distribution
using various extractions of nonperturbative NRQCD
long-distance matrix elements (LDMEs) in the literature.
NRQCD calculations agree with LHCb data better than default
pythia regardless of which fit to the LDMEs is used. LDMEs
from fits that focus exclusively on high transverse momentum
data from colliders are in good agreement with the LHCb
measurement.},
Doi = {10.1103/physrevlett.119.032002},
Key = {fds328273}
}
@article{fds3907,
Author = {T. Mehen and I.W. Stewart},
Title = {Nucleon-Nucleon Effective Field Theory at NNLO: Radiation
Pions and $^1S_0$ Phase Shift},
Series = {Proc. Inst. Nucl. Theor. 9},
Booktitle = {Proceedings of the INT Workshop on Nuclear Physics with
Effective Field Theory},
Publisher = {World Scientific},
Editor = {P. Bedaque and M. Savage and R. Seki and U. L. Van
Kolck},
Year = {2000},
Abstract = {Low energy phenomena involving two nucleons can be
successfully described using effective field theory. Because
of the relatively large expansion parameter, it is only at
next-to-next-to-leading order (NNLO) where one can expect to
see agreement with experiment at the few percent level. The
first part of this talk will focus on radiation pion
effects, which first appear at NNLO. The power counting for
radiation pions is simple for center of mass momentum
p~\sqrt{M m_pi}=Q_r, the threshold for pion production. We
explain how graphs calculated with the Q_r power counting
scale for p~m_\pi. The Q_r^3 radiation pion contributions to
nucleon-nucleon scattering are suppressed by inverse powers
of the S-wave scattering lengths. However, we point out that
order Q_r^4 radiation contributions might give a NNLO
contribution for p~m_pi. In the second part of the talk,
results for the potential pion and contact interaction part
of the NNLO 1S0 phase shift are presented. We emphasize the
importance of eliminating spurious poles in the expression
for the amplitude at each order in the perturbative
expansion. Doing this leaves a total of three free
parameters at NNLO. We obtain a good fit to the 1S0 phase
shift.},
Key = {fds3907}
}
@article{fds287641,
Author = {Kim, C and Mehen, T},
Title = {Octetonium at the LHC},
Journal = {Nuclear Physics B - Proceedings Supplements},
Volume = {200-202},
Number = {1 C},
Pages = {179-182},
Publisher = {Elsevier BV},
Year = {2010},
Month = {March},
ISSN = {0920-5632},
url = {http://arXiv.org/abs/0909.5695},
Abstract = {Several models of new physics, such as grand unified
theories, Pati-Salam models, chiral color models, etc.,
predict the existence of an SU(2)L doublet of color-octet
scalars (COS). In the Manohar-Wise model, the Yukawa
couplings of the COS are assumed to be consistent with
Minimal Flavor Violation ensuring constraints from flavor
physics are satisfied even for relatively light scalars. In
this simple model we consider the production of color
singlet bound states of COS that we call octetonium.
Octetonium are mainly produced via gluon-gluon fusion and
have significant production cross sections at the LHC. They
can decay to pairs of gluons or electroweak gauge bosons. If
the masses of the octetonia are 1 TeV or less, these states
will be visible as resonances in γγ, W+W-, ZZ, and γZ. ©
2010 Elsevier B.V.},
Doi = {10.1016/j.nuclphysbps.2010.02.081},
Key = {fds287641}
}
@article{fds152772,
Author = {Thomas Mehen},
Title = {On non-relativistic conformal field theory and trapped
atoms: Virial theorems and the state-operator correspondence
in three dimensions},
Journal = {Phys. Rev. A 78, 013614},
Year = {2008},
url = {http://arXiv.org/abs/0712.0867},
Abstract = {The field theory of nonrelativistic fermions interacting via
contact interactions can be used to calculate the properties
of few-body systems of cold atoms confined in harmonic
traps. The state-operator correspondence of Non-Relativistic
Conformal Field Theory (NRCFT) shows that the energy
eigenvalues (in oscillator units) of N harmonically trapped
fermions can be calculated from the scaling dimensions of
N-fermion operators in the NRCFT. They are also in
one-to-one correspondence with zero-energy, scale-invariant
solutions to the N-body problem in free space. We show that
these two mappings of the trapped fermion problem to free
space problems are related by an automorphism of the SL(2,R)
algebra of the conformal symmetry of fermions at the unitary
limit. This automorphism exchanges the internal Hamiltonian
of the gas with the trapping potential and hence provides a
novel method for deriving virial theorems for trapped Fermi
gases at the unitary limit. We also show that the
state-operator correspondence can be applied directly in
three spatial dimensions by calculating the scaling
dimensions of two- and three-fermion operators and finding
agreement with known exact results for energy levels of two
and three trapped fermions at the unitary
limit.},
Key = {fds152772}
}
@article{fds287658,
Author = {Idilbi, A and Mehen, T},
Title = {On the equivalence of soft and zero-bin subtractions},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {75},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2007},
Month = {June},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/hep-ph/0702022},
Abstract = {Zero-bin subtractions are required to avoid double counting
soft contributions in collinear loop integrals in
soft-collinear effective theory (SCET). In traditional
approaches to factorization, double counting is avoided by
dividing jet functions by matrix elements of soft Wilson
lines. In this paper, we compare the two approaches to
double counting, studying the quark form factor and deep
inelastic scattering (DIS) as xB→1 as examples. We explain
how the zero-bin subtractions in SCET are required to
reproduce the well-established factorization theorem for DIS
as xB→1. We study one-loop virtual contributions to the
quark form factor and real gluon emission diagrams in DIS.
The two approaches to double counting are equivalent if
dimensional regularization (DR) is used to regulate infrared
(IR) divergences. We discuss in detail ambiguities in the
calculation of one-loop scaleless integrals in DR in SCET
and perturbative QCD. We also demonstrate a nontrivial check
of the equivalence of the zero-bin subtraction and the soft
Wilson line subtraction in the virtual two-loop Abelian
contributions to the quark form factor. © 2007 The American
Physical Society.},
Doi = {10.1103/PhysRevD.75.114017},
Key = {fds287658}
}
@article{fds287647,
Author = {Mehen, T and Yang, D-L},
Title = {On the Role of Charmed Meson Loops in Charmonium
Decays},
Journal = {Phys.Rev. D85:014002},
Volume = {85},
Number = {1},
Year = {2012},
url = {http://arxiv.org/abs/1111.3884},
Abstract = {We investigate the effect of intermediate charmed meson
loops on the M1 radiative decays J/ψ→η cγ and ψ
′→ηc(′)γ as well as the isospin [SU(3)] violating
hadronic decays ψ ′→J/ψπ0(η) using heavy hadron
chiral perturbation theory. The calculations include tree
level as well as one loop diagrams and are compared to the
latest data from CLEO and BES-III. Our fit constrains the
couplings of 1S and 2S charmonium multiplets to charmed
mesons, denoted g 2 and g2′, respectively. We find that
there are two sets of solutions for g 2 and g2′. One set,
which agrees with previous values of the product g 2g2′
extracted from analyses that consider only loop
contributions to ψ ′→ J/ψπ0(η), can only fit data on
radiative decays with fine-tuned cancellations between tree
level diagrams and loops in that process. The other solution
for g 2 and g2′ leads to couplings that are smaller by a
factor of 2.3. In this case tree level and loop
contributions are of comparable size and the numerical
values of the tree level contributions to radiative decays
are consistent with estimates based on the quark model as
well as nonrelativistic QCD. This result shows that tree
level heavy hadron chiral perturbation theory couplings are
as important as the one loop graphs with charmed mesons in
these charmonium decays. The couplings g 2 and g2′ are
also important for the calculations of the decays of charmed
meson bound states, such as the X(3872), to conventional
charmonia. © 2012 American Physical Society.},
Doi = {10.1103/PhysRevD.85.014002},
Key = {fds287647}
}
@article{fds305716,
Author = {Aharony, O and Gomis, J and Mehen, T},
Title = {On theories with light-like noncommutativity},
Journal = {Journal of High Energy Physics},
Volume = {4},
Number = {9 PART A},
Pages = {XXXII-14},
Year = {2000},
Abstract = {We show that field theories with light-like
noncommutativity, that is with θ0i = θ1i, are unitary
quantum theories, and that they can be obtained as decoupled
field theory limits of string theory with D-branes in a
background NS-NS B-field. For general noncommutativity
parameters, we show that non-commutative field theories
which are unitary can be obtained as decoupled field theory
limits of string theory, while those that are not unitary
cannot be obtained from string theory because massive open
strings do not decouple. We study the different theories
with light-like noncommutativity which arise from type-II
D-branes. The decoupling limit of the D4-brane seems to lead
to a non-commutative field theory deformation of the (2,0)
SCFT of M5-branes, while the D5-brane case leads to a
non-commutative variation of "little string theories". We
discuss the DLCQ description of these theories.},
Key = {fds305716}
}
@article{fds287690,
Author = {Aharony, O and Gomis, J and Mehen, T},
Title = {On Theories with Lightlike Noncommutativity},
Journal = {JHEP},
Volume = {9},
Number = {9 PART A},
Pages = {23},
Year = {2000},
url = {http://dx.doi.org/10.1088/1126-6708/2000/09/023},
Abstract = {We show that field theories with light-like
noncommutativity, that is with $\theta^{0i}=-\theta^{1i}$,
are unitary quantum theories, and that they can be obtained
as decoupled field theory limits of string theory with
D-branes in a background NS-NS $B$ field. For general
noncommutativity parameters, we show that noncommutative
field theories which are unitary can be obtained as
decoupled field theory limits of string theory, while those
that are not unitary cannot be obtained from string theory
because massive open strings do not decouple. We study the
different theories with light-like noncommutativity which
arise from Type II D-branes. The decoupling limit of the
D4-brane seems to lead to a noncommutative field theory
deformation of the $(2,0)$ SCFT of M5-branes, while the
D5-brane case leads to a noncommutative variation of
``little string theories''. We discuss the DLCQ description
of these theories.},
Doi = {10.1088/1126-6708/2000/09/023},
Key = {fds287690}
}
@article{fds354586,
Author = {Dai, L and Low, I and Mehen, T and Mohapatra, A},
Title = {Operator counting and soft blocks in chiral perturbation
theory},
Journal = {Physical Review D},
Volume = {102},
Number = {11},
Year = {2020},
Month = {December},
url = {https://arxiv.org/abs/2009.01819},
Abstract = {Chiral perturbation theory (ChPT) is a low-energy effective
field theory of QCD and also a nonlinear sigma model based
on the symmetry breaking pattern SU(Nf)×SU(Nf)→SU(Nf). In
the limit of massless Nf quarks, we enumerate the
independent operators without external sources in ChPT using
an on-shell method, by counting and presenting the soft
blocks at each order in the derivative expansion, up to
O(p10). Given the massless on-shell condition and total
momentum conservation, soft blocks are homogeneous
polynomials of kinematic invariants exhibiting Adler's zero
when any external momentum becomes soft and vanishing. In
addition, soft blocks are seeds for recursively generating
all tree amplitudes of Nambu-Goldstone bosons without
recourse to ChPT, and in one-to-one correspondence with the
"low-energy constants"which are the Wilson coefficients.
Relations among operators, such as those arising from
equations of motion, integration by parts, Hermiticity, and
symmetry structure, manifest themselves in the soft blocks
in simple ways. We find agreements with the existing results
up to next-to-next-to-next-to-leading order (NNNLO) and make
a prediction at N4LO.},
Doi = {10.1103/PhysRevD.102.116011},
Key = {fds354586}
}
@article{fds287650,
Author = {Idilbi, A and Kim, C and Mehen, T},
Title = {Pair production of color-octet scalars at the
LHC},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {82},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2010},
Month = {October},
ISSN = {1550-7998},
url = {http://hdl.handle.net/10161/4280 Duke open
access},
Abstract = {Heavy colored scalar particles, which exist in many models
of new physics, can be pair produced at the LHC via
gluon-gluon fusion and possibly form quarkoniumlike bound
states. If the scalars are also charged under the
electroweak gauge group, these bound states can then decay
into electroweak bosons. This yields a resonant cross
section for final states such as γγ that can exceed
standard model backgrounds. This paper studies this process
in the Manohar-Wise model of color-octet scalars (COS).
Important threshold logarithms and final state Coulomb-like
QCD interactions are resummed using effective field theory.
We compute the resummed cross section for gluon-gluon fusion
to COS pairs at the LHC as well as the resonant cross
section for octetonium decaying to γγ. The latter cross
section exceeds the standard model diphoton cross section
when the COS mass is less than 500 (350) GeV for
√s=14(7)TeV. Nonobservation of resonances below these
energies can significantly improve existing bounds on COS
masses. © 2010 The American Physical Society.},
Doi = {10.1103/PhysRevD.82.075017},
Key = {fds287650}
}
@article{fds346864,
Author = {Mehen, T and Mohapatra, A},
Title = {Perturbative corrections to heavy quark-diquark symmetry
predictions for doubly heavy baryon hyperfine
splittings},
Journal = {Physical Review D},
Volume = {100},
Number = {7},
Year = {2019},
Month = {October},
url = {http://dx.doi.org/10.1103/PhysRevD.100.076014},
Abstract = {Doubly heavy baryons (QQq) and singly heavy antimesons (Qq)
are related by the heavy quark-diquark (HQDQ) symmetry
because in the mQ→∞ limit, the light degrees of freedom
(d.o.f.) in both the hadrons are expected to be in identical
configurations. Hyperfine splittings of the ground states in
both systems are nonvanishing at O(1/mQ) in the heavy quark
mass expansion, and HQDQ symmetry relates the hyperfine
splittings in the two sectors. In this paper, working within
the framework of nonrelativistic QCD (NRQCD), we point out
the existence of an operator that couples four heavy quark
fields to the chromomagnetic field with a coefficient that
is enhanced by a factor from Coulomb exchange. This operator
gives a correction to doubly heavy baryon hyperfine
splittings that scales as 1/mQ2×αS/r, where r is the
separation between the heavy quarks in the diquark. This
correction can be calculated analytically in the extreme
heavy quark limit in which the potential between the quarks
in the diquark is Coulombic. In this limit, the correction
is O(αs2/mQ) and comes with a small coefficient. For values
of αs relevant to doubly charm and doubly bottom systems,
the correction to the hyperfine splittings in doubly heavy
baryons is only a few percent or smaller. We also argue that
nonperturbative corrections to the prediction for the
hyperfine splittings are suppressed by ΛQCD2/mQ2 rather
than ΛQCD/mQ. Corrections should be ≈10% in the charm
sector and smaller in heavier systems.},
Doi = {10.1103/PhysRevD.100.076014},
Key = {fds346864}
}
@article{fds340923,
Author = {Fleming, S and Mehen, T},
Title = {Photoproduction of (Formula Presented)},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {58},
Number = {3},
Pages = {4},
Year = {1998},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevD.58.037503},
Abstract = {Using the NRQCD factorization formalism, we calculate the
total cross section for the photoproduction of (Formula
presented) mesons. We include color-octet and color-singlet
mechanisms as well as next-to-leading order perturbative QCD
corrections. The theoretical prediction depends on two
nonperturbative matrix elements that are not well determined
from existing data on charmonium production. For reasonable
values of these matrix elements, the cross section is large
enough that the (Formula presented) may be observable at the
E831 experiment and at the DESY HERA experiments. © 1998
The American Physical Society.},
Doi = {10.1103/PhysRevD.58.037503},
Key = {fds340923}
}
@booklet{Fleming98,
Author = {Fleming, S and Mehen, T},
Title = {Photoproduction of h(c)},
Journal = {Physical Review D},
Volume = {5803},
Number = {3},
Pages = {art. no.-037503},
Year = {1998},
Month = {August},
ISSN = {0556-2821},
Abstract = {Using the NRQCD factorization formalism, we calculate the
total cross section for the photoproduction of h c mesons.
We include color-octet and color-singlet mechanisms as well
as next-to-leading order perturbative QCD corrections. The
theoretical prediction depends on two nonperturbative matrix
elements that are not well determined from existing data on
charmonium production. For reasonable values of these matrix
elements, the cross section is large enough that the h c may
be observable at the E831 experiment and at the DESY HERA
experiments.},
Key = {Fleming98}
}
@article{fds305712,
Author = {Fleming, S and Mehen, T},
Title = {Photoproduction of hc},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {58},
Number = {3},
Pages = {0375031-0375034},
Year = {1998},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.58.037503},
Abstract = {Using the NRQCD factorization formalism, we calculate the
total cross section for the photoproduction of hc mesons. We
include color-octet and color-singlet mechanisms as well as
next-to-leading order perturbative QCD corrections. The
theoretical prediction depends on two nonperturbative matrix
elements that are not well determined from existing data on
charmonium production. For reasonable values of these matrix
elements, the cross section is large enough that the hc may
be observable at the E831 experiment and at the DESY HERA
experiments.},
Doi = {10.1103/PhysRevD.58.037503},
Key = {fds305712}
}
@article{fds287656,
Author = {Fleming, S and Kusunoki, M and Mehen, T and Van Kolck,
U},
Title = {Pion interactions in the X(3872)},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {76},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2007},
Month = {August},
ISSN = {1550-7998},
url = {http://arXiv.org/abs/hep-ph/0703168},
Abstract = {We consider pion interactions in an effective field theory
of the narrow resonance X(3872), assuming it is a weakly
bound molecule of the charm mesons D0D̄*0 and D*0D̄0.
Since the hyperfine splitting of the D0 and D*0 is only 7
MeV greater than the neutral pion mass, pions can be
produced near threshold and are nonrelativistic. We show
that pion exchange can be treated in perturbation theory and
calculate the next-to-leading-order correction to the
partial decay width Γ[X→D0D̄0π0]. © 2007 The American
Physical Society.},
Doi = {10.1103/PhysRevD.76.034006},
Key = {fds287656}
}
@article{fds376734,
Author = {Copeland, M and Fleming, S and Gupta, R and Hodges, R and Mehen,
T},
Title = {Polarized TMD fragmentation functions for J/ψ
production},
Journal = {Physical Review D},
Volume = {109},
Number = {5},
Year = {2024},
Month = {March},
url = {https://inspirehep.net/literature/2689297},
Abstract = {We calculate the matching, at leading order, of the
transverse momentum-dependent fragmentation functions
(TMDFFs) for light quarks and gluons fragmenting to a J/ψ
onto polarized nonrelativistic QCD (NRQCD) TMDFFs. The NRQCD
TMDFFs have an operator product expansion in terms of
nonperturbative NRQCD production matrix elements. Using the
results we obtain, we make predictions for the light quark
fragmentation contribution to the production of polarized
J/ψ in semi-inclusive deep inelastic scattering (SIDIS)
both for unpolarized and longitudinally polarized beams.
These results are an important contribution to polarized
J/ψ production in SIDIS and thus are needed for comparison
with experiments at the future Electron-Ion
Collider.},
Doi = {10.1103/PhysRevD.109.054017},
Key = {fds376734}
}
@article{fds287614,
Author = {Baumgart, M and Leibovich, AK and Mehen, T and Rothstein,
IZ},
Title = {Probing quarkonium production mechanisms with jet
substructure},
Journal = {Journal of High Energy Physics},
Volume = {2014},
Number = {11},
Publisher = {Springer Nature},
Year = {2014},
Month = {November},
url = {http://arxiv.org/abs/arXiv:1406.2295},
Abstract = {We use fragmenting jet functions (FJFs) in the context of
quarkonia to study the production channels predicted by
NRQCD (3S1(1), 3S1(8), 1S0(8), 3PJ(8)). We choose a set of
FJFs that give the probability to find a quarkonium with a
given momentum fraction inside a cone-algorithm jet with
fixed cone size and energy. This observable gives several
lever arms that allow one to distinguish different
production channels. In particular, we show that at fixed
momentum fraction the individual production mechanisms have
distinct behaviors as a function of the the jet energy. As a
consequence of this fact, we arrive at the robust prediction
that if the depolarizing 1S0(8) matrix element dominates,
then the gluon FJF will diminish with increasing energy for
fixed momentum fraction, z, and z >0.5.},
Doi = {10.1007/JHEP11(2014)003},
Key = {fds287614}
}
@article{fds287618,
Author = {Kim, C and Idilbi, A and Mehen, T and Yoon, YW},
Title = {Production of stoponium at the LHC},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {89},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2014},
Month = {April},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/arXiv:1401.1284},
Abstract = {Although the Large Hadron Collider (LHC) has not observed
supersymmetric (SUSY) partners of the Standard Model
particles, their existence is not ruled out yet. One
recently explored scenario in which there are light SUSY
partners that have evaded current bounds from the LHC is
that of a light long-lived stop quark. In this paper we
consider light stop pair production at the LHC when the stop
mass is between 200 and 400 GeV. If the stops are long-lived
they can form a bound state, stoponium, which then undergoes
two-body decays to Standard Model particles. By considering
the near-threshold production of such a pair through the
gluon-gluon fusion process and taking into account the
strong Coulombic interactions responsible for the formation
of this bound state, we obtain factorization theorems for
the stop pair inclusive and differential production cross
sections. We also perform a resummation of large threshold
logarithms up to next-to-next-to-leading logarithmic
accuracy using well-established renormalization group
equations in an effective field theory methodology. These
results are used to calculate the invariant mass
distributions of two photons or two Z bosons coming from the
decay of the stoponium at the LHC. For our choices of SUSY
model parameters, the stoponium is not detectable above
Standard Model backgrounds in γγ or ZZ at 8 TeV, but will
be visible with 400fb-1 of accumulated data if its mass is
below 500 GeV when the LHC runs at 14 TeV. © 2014 American
Physical Society.},
Doi = {10.1103/PhysRevD.89.075010},
Key = {fds287618}
}
@article{fds359291,
Author = {Chapon, É and d'Enterria, D and Ducloué, B and Echevarria, MG and Gossiaux, PB and Kartvelishvili, V and Kasemets, T and Lansberg, JP and McNulty, R and Price, DD and Shao, HS and Van Hulse and C and Winn, M and Adam, J and An, L and Villar, DYA and Bhattacharya, S and Celiberto, FG and Cheshkov, C and D'Alesio, U and da Silva, C and Ferreiro, EG and Flett,
CA and Flore, C and Garzelli, MV and Gaunt, J and He, J and Makris, Y and Marquet, C and Massacrier, L and Mehen, T and Mezrag, C and Micheletti,
L and Nagar, R and Nefedov, MA and Ozcelik, MA and Paul, B and Pisano, C and Qiu, JW and Rajesh, S and Rinaldi, M and Scarpa, F and Smith, M and Taels,
P and Tee, A and Teryaev, O and Vitev, I and Watanabe, K and Yamanaka, N and Yao, X and Zhang, Y},
Title = {Prospects for quarkonium studies at the high-luminosity
LHC},
Journal = {Progress in Particle and Nuclear Physics},
Volume = {122},
Year = {2022},
Month = {January},
url = {http://dx.doi.org/10.1016/j.ppnp.2021.103906},
Abstract = {Prospects for quarkonium-production studies accessible
during the upcoming high-luminosity phases of the CERN Large
Hadron Collider operation after 2021 are reviewed. Current
experimental and theoretical open issues in the field are
assessed together with the potential for future studies in
quarkonium-related physics. This will be possible through
the exploitation of the huge data samples to be collected in
proton–proton, proton–nucleus and nucleus–nucleus
collisions, both in the collider and fixed-target modes.
Such investigations include, among others, those of: (i)
J/ψ and Υ produced in association with other hard
particles; (ii) χc,b and ηc,b down to small transverse
momenta; (iii) the constraints brought in by quarkonia on
gluon PDFs, nuclear PDFs, TMDs, GPDs and GTMDs, as well as
on the low-x parton dynamics; (iv) the gluon Sivers effect
in polarised-nucleon collisions; (v) the properties of the
quark–gluon plasma produced in ultra-relativistic
heavy-ion collisions and of collective partonic effects in
general; and (vi) double and triple parton
scatterings.},
Doi = {10.1016/j.ppnp.2021.103906},
Key = {fds359291}
}
@article{fds305713,
Author = {Gomis, J and Mehen, T and Wise, MB},
Title = {Quantum field theories with compact non-commutative extra
dimensions},
Journal = {Journal of High Energy Physics},
Volume = {4},
Number = {8 PART B},
Pages = {1-15},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1088/1126-6708/2000/08/029},
Abstract = {We study field theories on spaces with additional compact
noncommutative dimensions. As an example, we study φ3 on
ℝ1,3xdouble-struck T signθ2 using perturbation theory.
The infrared divergences in the non-compact theory give rise
to unusual dynamics for the mode of φ which is constant
along the torus. Correlation functions involving this mode
vanish. Moreover, we show that the spectrum of Kaluza-Klein
excitations can be very different from the analogous
commuting theory. There is an additional contribution to the
Kaluza-Klein mass formula that resembles the contribution of
winding states in string theory. We also consider the effect
of noncommutativity on the four-dimensional Kaluza-Klein
excitations of a six-dimensional gauge field.},
Doi = {10.1088/1126-6708/2000/08/029},
Key = {fds305713}
}
@article{fds287689,
Author = {Gomis, J and Mehen, T and Wise, MB},
Title = {Quantum Field Theories with Compact Noncommutative Extra
Dimensions},
Journal = {JHEP},
Volume = {8},
Number = {8},
Pages = {29},
Year = {2000},
Abstract = {We study field theories on spaces with additional compact
noncommutative dimensions. As an example, we study \phi^3 on
R^{1,3}\times T^{2}_\theta using perturbation theory. The
infrared divergences in the noncompact theory give rise to
unusual dynamics for the mode of \phi which is constant
along the torus. Correlation functions involving this mode
vanish. Moreover, we show that the spectrum of Kaluza-Klein
excitations can be very different from the analogous
commuting theory. There is an additional contribution to the
Kaluza-Klein mass formula that resembles the contribution of
winding states in string theory. We also consider the effect
of noncommutativity on the four dimensional Kaluza-Klein
excitations of a six dimensional gauge field.},
Key = {fds287689}
}
@article{fds343714,
Author = {Yao, X and Mehen, T},
Title = {Quarkonium in-medium transport equation derived from first
principles},
Journal = {Physical Review D},
Volume = {99},
Number = {9},
Year = {2019},
Month = {May},
url = {http://dx.doi.org/10.1103/PhysRevD.99.096028},
Abstract = {We use the open quantum system formalism to study the
dynamical in-medium evolution of quarkonium. The system of
quarkonium is described by potential nonrelativistic QCD
while the environment is a weakly coupled quark-gluon plasma
in local thermal equilibrium below the melting temperature
of the quarkonium. Under the Markovian approximation, it is
shown that the Lindblad equation leads to a Boltzmann
transport equation if a Wigner transform is applied to the
system density matrix. Our derivation illuminates how the
microscopic time reversibility of QCD is consistent with the
time-irreversible in-medium evolution of quarkonium states.
Static screening, dissociation, and recombination of
quarkonium are treated in the same theoretical framework. In
addition, quarkonium annihilation is included in a similar
way, although the effect is negligible for the phenomenology
of the current heavy ion collision experiments. The methods
used here can be extended to study quarkonium dynamical
evolution inside a strongly coupled QGP, a hot medium out of
equilibrium, or cold nuclear matter, which is important to
studying quarkonium production in heavy ion, proton-ion, and
electron-ion collisions.},
Doi = {10.1103/PhysRevD.99.096028},
Key = {fds343714}
}
@article{fds354150,
Author = {Yao, X and Ke, W and Xu, Y and Bass, SA and Mehen, T and Müller,
B},
Title = {Quarkonium Production in Heavy Ion Collisions: From Open
Quantum System to Transport Equation},
Year = {2020},
Month = {February},
url = {https://arxiv.org/abs/2002.04079},
Abstract = {Using the open quantum system formalism and effective field
theory of QCD, we derive the Boltzmann transport equation of
quarkonium inside the quark-gluon plasma. Our derivation
illuminates that the success of transport equations in
quarkonium phenomenology is closely related to the
separation of scales in the problem.},
Key = {fds354150}
}
@article{fds355265,
Author = {Mehen, T and Yao, X},
Title = {Quarkonium Semiclassical Transport in Quark Gluon Plasma:
Factorization and Quantum Correction},
Volume = {2},
Number = {062},
Year = {2021},
Month = {February},
url = {https://arxiv.org/abs/2009.02408},
Abstract = {We study quarkonium transport in the quark-gluon plasma by
using the potential nonrelativistic QCD (pNRQCD) effective
field theory and the framework of open quantum systems. We
argue that the coupling between quarkonium and the thermal
bath is weak using separation of scales, so the initial
density matrix of the total system factorizes and the time
evolution of the subsystem is Markovian. We derive the
semiclassical Boltzmann equation for quarkonium by applying
a Wigner transform to the Lindblad equation and carrying out
a semiclassical expansion. We resum relevant interactions to
all orders in the coupling constant at leading power of the
nonrelativistic and multipole expansions. The derivation is
valid for both weakly coupled and strongly coupled
quark-gluon plasmas. We find reaction rates in the transport
equation factorize into a quarkonium dipole transition
function and a chromoelectric gluon distribution function.
For the differential reaction rate, the definition of the
momentum dependent chromoelectric gluon distribution
function involves staple-shaped Wilson lines. For the
inclusive reaction rate, the Wilson lines collapse into a
straight line along the real time axis and the distribution
becomes momentum independent. The relation between the two
Wilson lines is analogous to the relation between the Wilson
lines appearing in the gluon parton distribution function
(PDF) and the gluon transverse momentum dependent parton
distribution function (TMDPDF). The centrality dependence of
the quarkonium nuclear modification factor measured by
experiments probes the momentum independent distribution
while the transverse momentum dependence and measurements of
the azimuthal angular anisotropy may be able to probe the
momentum dependent one. We discuss one way to indirectly
constrain the quarkonium in-medium real potential by using
the factorization formula and lattice calculations. The
leading quantum correction to the semiclassical transport
equation of quarkonium is also worked out. The study can be
easily generalized to quarkonium transport in cold nuclear
matter, which is relevant for quarkonium production in eA
collisions in the future Electron-Ion Collider.},
Doi = {10.1007/JHEP02(2021)062},
Key = {fds355265}
}
@article{fds287670,
Author = {Mehen, T and Tiburzi, BC},
Title = {Quarks with twisted boundary conditions in the epsilon
regime},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {72},
Number = {1},
Pages = {1-9},
Publisher = {American Physical Society (APS)},
Year = {2005},
Month = {July},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/hep-lat/0505014},
Abstract = {We study the effects of twisted boundary conditions on the
quark fields in the epsilon regime of chiral perturbation
theory. We consider the SU(2)LxSU(2)R chiral theory with
nondegenerate quarks and the SU(3)LxSU(3)R chiral theory
with massless up and down quarks and massive strange quarks.
The partition function and condensate are derived for each
theory. Because flavor-neutral Goldstone bosons are
unaffected by twisted boundary conditions chiral symmetry is
still restored in finite volumes. The dependence of the
condensate on the twisting parameters can be used to extract
the pion decay constant from simulations in the epsilon
regime. The relative contribution to the partition function
from sectors of different topological charge is numerically
insensitive to twisted boundary conditions. © 2005 The
American Physical Society.},
Doi = {10.1103/PhysRevD.72.014501},
Key = {fds287670}
}
@article{fds287682,
Author = {Mehen, T and Stewart, IW},
Title = {Radiation pions in two-nucleon effective field
theory},
Journal = {Nuclear Physics A},
Volume = {665},
Number = {1-2},
Pages = {164-182},
Publisher = {Elsevier BV},
Year = {2000},
Month = {February},
url = {http://dx.doi.org/10.1016/S0375-9474(99)00368-1},
Abstract = {For interactions involving two or more nucleons it is useful
to divide pions into three classes: potential, radiation,
and soft. The momentum threshold for the production of
radiation pions is Qr = √ MNmπ. We show that radiation
pions can be included systematically with a power counting
in Qr. The leading order radiation pion graphs which
contribute to NN scattering are evaluated in the PDS and OS
renormalization schemes and are found to give a small
contribution. The power counting for soft pion contributions
is also discussed. © 2000 Elsevier Science B.V. All rights
reserved.},
Doi = {10.1016/S0375-9474(99)00368-1},
Key = {fds287682}
}
@article{fds305720,
Author = {Mehen, T and Springer, R},
Title = {Radiative decays X(3872)→ψ(2S)γ and ψ(4040)→X(3872)
γ in effective field theory},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {83},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {May},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.83.094009},
Abstract = {Heavy hadron chiral perturbation theory (HHχPT) and XEFT
are applied to the decays X(3872)→ψ(2S)γ and
ψ(4040)→X(3872)γ under the assumption that the X(3872)
is a molecular bound state of neutral charm mesons. In these
decays the emitted photon energies are 181MeV and 165MeV,
respectively, so HHχPT can be used to calculate the
underlying D0D ̄0*+D̄0D0 *→ψ(2S)γ or ψ(4040)→(D0D
̄0*+D̄0D0*) γ transition. These amplitudes are matched
onto XEFT to obtain decay rates. The decays receive
contributions from both long-distance and short-distance
processes. We study the polarization of the ψ(2S) in the
decay X(3872)→ψ(2S)γ and the angular distribution of
X(3872) in the decay ψ(4040)→X(3872)γ and find they can
be used to differentiate between different decay mechanisms
as well as discriminate between 2-+ and 1++ quantum number
assignments of the X(3872). © 2011 American Physical
Society.},
Doi = {10.1103/PhysRevD.83.094009},
Key = {fds305720}
}
@article{fds287692,
Author = {Hammer, HW and Mehen, T},
Title = {Range corrections to doublet S-wave neutron-deuteron
scattering},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {516},
Number = {3-4},
Pages = {353-361},
Publisher = {Elsevier BV},
Year = {2001},
Month = {September},
ISSN = {0370-2693},
url = {http://dx.doi.org/10.1016/S0370-2693(01)00918-2},
Abstract = {We calculate the range corrections to S-wave
neutron-deuteron scattering in the doublet channel (S = 1/2)
to first order in r/a where a is the scattering length and r
the effective range. Ultraviolet divergences appearing at
this order can be absorbed into a redefinition of the
leading order three-body force. The corrections to the
elastic scattering amplitude below the deuteron breakup
threshold are computed. Inclusion of the range corrections
gives good agreement with measured scattering data and
potential model calculations. © 2001 Elsevier Science B.V.
All rights reserved.},
Doi = {10.1016/S0370-2693(01)00918-2},
Key = {fds287692}
}
@article{fds287664,
Author = {Mehen, T},
Title = {Recent developments in heavy quark and quarkonium
production},
Journal = {Acta Physica Polonica B},
Volume = {35},
Number = {1},
Pages = {121-129},
Year = {2004},
Month = {January},
ISSN = {0587-4254},
url = {http://arxiv.org/abs/hep-ph/0312239},
Abstract = {Recent measurements of J/ψ production in e+e- colliders
pose a challenge to the NRQCD factorization theorem for
quarkonium production. Discrepancies between leading order
calculations of color-octet contributions and the momentum
distribution of J/ψ observed by Belle and BaBar are
resolved by resumming large perturbative and nonperturbative
corrections that are enhanced near the kinematic endpoint.
The large cross sections for J/ψcc̄ and double quarkonium
production remain poorly understood. Nonperturbative effects
in fixed-target hadroproduction of open charm are also
discussed. Large asymmetries in the production of charm
mesons and baryons probe nonperturbative corrections to the
QCD factorization theorem. A power correction called
heavy-quark recombination can economically explain these
asymmetries with a few universal parameters.},
Key = {fds287664}
}
@article{fds287681,
Author = {Mehen, T and Stewart, IW},
Title = {Renormalization schemes and the range of two-nucleon
effective field theory},
Journal = {Physical Review C - Nuclear Physics},
Volume = {59},
Number = {5},
Pages = {2365-2383},
Publisher = {American Physical Society (APS)},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevC.59.2365},
Abstract = {The off-shell momentum subtraction (OS) and power divergence
subtraction (PDS) renormalization schemes for the effective
field theory with nucleons and pions are investigated. We
explain in detail how the renormalization is implemented
using local counterterms. Fits to the [Formula Presented]
scattering data are performed in the [Formula Presented] and
[Formula Presented] channels for different values of
[Formula Presented] An error analysis indicates that the
range of the theory with perturbative pions is consistent
with [Formula Presented]. © 1999 The American Physical
Society.},
Doi = {10.1103/PhysRevC.59.2365},
Key = {fds287681}
}
@article{fds287660,
Author = {Manohar, AV and Mehen, T and Pirjol, D and Stewart,
IW},
Title = {Reparameterization invariance for collinear
operators},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {539},
Number = {1-2},
Pages = {59-66},
Publisher = {Elsevier BV},
Year = {2002},
Month = {July},
ISSN = {0370-2693},
url = {http://arxiv.org/abs/hep-ph/0204229},
Abstract = {We discuss restrictions on operators in the soft-collinear
effective theory (SCET) which follow from the ambiguity in
the decomposition of collinear momenta and the freedom in
the choice of light-like basis vectors n and n̄. Invariance
of SCET under small changes in n and/or n̄ implies a
symmetry of the effective theory that constrains the form of
allowed operators with collinear fields. The restrictions
occur at a given order in the power counting as well as
between different orders. As an example, we present the
complete set of higher order operators that are related to
the collinear quark kinetic term. ©2002 Elsevier Science
B.V. All rights reserved.},
Doi = {10.1016/S0370-2693(02)02029-4},
Key = {fds287660}
}
@article{fds287661,
Author = {Fleming, S and Leibovich, AK and Mehen, T},
Title = {Resummation of large endpoint corrections to color-octet
J/ψ photoproduction},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {74},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2006},
Month = {December},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/hep-ph/0607121},
Abstract = {An unresolved problem in J/ψ phenomenology is a systematic
understanding of the differential photoproduction cross
section, dσ/dz[γ+p→J/ψ+X], where z=Eψ/Eγ in the
proton rest frame. In the nonrelativistic QCD (NRQCD)
factorization formalism, fixed-order perturbative
calculations of color-octet mechanisms suffer from large
perturbative and nonperturbative corrections that grow
rapidly in the endpoint region, z→1. In this paper, NRQCD
and soft collinear effective theory are combined to resum
these large corrections to the color-octet photoproduction
cross section. We derive a factorization theorem for the
endpoint differential cross section involving the parton
distribution function and the color-octet J/ψ shape
functions. A one-loop matching calculation explicitly
confirms our factorization theorem at next-to-leading order.
Large perturbative corrections are resummed using the
renormalization group. The calculation of the color-octet
contribution to dσ/dz is in qualitative agreement with
data. Quantitative tests of the universality of color-octet
matrix elements require improved knowledge of shape
functions entering these calculations as well as resummation
of the color-singlet contribution which accounts for much of
the total cross section and also peaks near the endpoint. ©
2006 The American Physical Society.},
Doi = {10.1103/PhysRevD.74.114004},
Key = {fds287661}
}
@article{fds287671,
Author = {Fleming, S and Leibovich, AK and Mehen, T},
Title = {Resumming the color-octet contribution to [Formula
Presented]},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {68},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2003},
Month = {January},
ISSN = {0556-2821},
url = {http://arxiv.org/abs/hep-ph/0306139},
Abstract = {Recent observations of the spectrum of [Formula Presented]
produced in [Formula Presented] collisions at the [Formula
Presented] resonance are in conflict with fixed-order
calculations using the nonrelativistic QCD effective field
theory. One problem is that leading order color-octet
mechanisms predict an enhancement of the cross section for
[Formula Presented] with a maximal energy that is not
observed in the data. However, in this region of phase space
large perturbative corrections (Sudakov logarithms) as well
as enhanced nonperturbative effects are important. In this
paper we use the newly developed soft-collinear effective
theory (SCET) to systematically include these effects. We
find that these corrections significantly broaden the
color-octet contribution to the [Formula Presented]
spectrum. Our calculation employs a one-stage
renormalization group evolution rather than the two-stage
evolution used in previous SCET calculations. We give a
simple argument for why the two methods yield identical
results to lowest order in the SCET power counting. © 2003
The American Physical Society.},
Doi = {10.1103/PhysRevD.68.094011},
Key = {fds287671}
}
@article{fds349390,
Author = {Dai, L and Guo, FK and Mehen, T},
Title = {Revisiting X (3872) →d0 D 0π0 in an effective field
theory for the X (3872) Revisiting X (3872) →d0 D 0π0 in
An Effective Field ... Dai Lin, Guo Feng-Kun, and Mehen
Thomas},
Journal = {Physical Review D},
Volume = {101},
Number = {5},
Year = {2020},
Month = {March},
url = {https://arxiv.org/abs/1912.04317},
Abstract = {The calculation of the decay X(3872)→D0D0π0 in effective
field theory is revisited to include final state π0D0,
π0D0 and D0D0 rescattering diagrams. These introduce
significant uncertainty into the prediction for the partial
width as a function of the binding energy. The differential
distribution in the pion energy is also studied for the
first time. The normalization of the distribution is again
quite uncertain due to higher order effects but the shape of
the distribution is unaffected by higher order corrections.
Furthermore the shape of the distribution and the location
of the peak are sensitive to the binding energy of X(3872).
The shape is strongly impacted by the presence of virtual
D∗0 graphs which highlights the molecular nature of the
X(3872). Measurement of the pion energy distribution in the
decay X(3872)→D0D0π0 can reveal interesting information
about the binding nature of the X(3872).},
Doi = {10.1103/PhysRevD.101.054024},
Key = {fds349390}
}
@booklet{Mehen96,
Author = {Mehen, T},
Title = {Scale setting in top quark decays},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {382},
Number = {3},
Pages = {267-272},
Publisher = {Elsevier BV},
Year = {1996},
Month = {August},
url = {http://dx.doi.org/10.1016/0370-2693(96)00681-8},
Abstract = {We compute the O(β0α2s) QCD corrections to the Standard
Model decay t → W+ b as well as the non standard decay t
→ H+ b. We then use our results to compute the BLM scale
for these decays, and study the dependence of the BLM scale
on the mass of the boson in the decay. We find that the BLM
procedure gives extremely small scales when top decays into
heavy bosons. When we try to improve the BLM scale by
reexpressing rates as a functions of the top quark running
mass, we find the BLM scale exhibits unnatural dependence on
the boson mass, casting doubts on the applicability of the
BLM procedure to these processes.},
Doi = {10.1016/0370-2693(96)00681-8},
Key = {Mehen96}
}
@article{fds287651,
Author = {Braaten, E and Hammer, HW and Mehen, T},
Title = {Scattering of an ultrasoft pion and the X(3872)},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {82},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2010},
Month = {August},
ISSN = {1550-7998},
url = {http://hdl.handle.net/10161/4278 Duke open
access},
Abstract = {The identification of the X(3872) as a loosely-bound
charm-meson molecule allows it to be described by an
effective field theory, called XEFT, for the D*D̄, DD̄*,
and DD̄π sector of QCD at energies small compared to the
pion mass. We point out that this effective field theory can
be extended to the sector that includes an additional pion
and used to calculate cross sections for the scattering of a
pion and the X(3872). If the collision energy is much
smaller than the pion mass, the cross sections are
completely calculable at leading order in terms of the
masses and widths of the charm mesons, pion masses, and the
binding energy of the X(3872). We carry out an explicit
calculation of the cross section for the breakup of the
X(3872) into D*+D̄*0 by the scattering of a very low energy
π+. ©2010 The American Physical Society.},
Doi = {10.1103/PhysRevD.82.034018},
Key = {fds287651}
}
@article{fds287688,
Author = {Gomis, J and Mehen, T},
Title = {Space-time noncommutative field theories and
unitarity},
Journal = {Nuclear Physics B},
Volume = {591},
Number = {1-2},
Pages = {265-276},
Publisher = {Elsevier BV},
Year = {2000},
Month = {December},
url = {http://dx.doi.org/10.1016/S0550-3213(00)00525-3},
Abstract = {We study the perturbative unitarity of noncommutative scalar
field theories. Field theories with space-time
noncommutativity do not have a unitary S-matrix. Field
theories with only space noncommutativity are perturbatively
unitary. This can be understood from string theory, since
space noncommutative field theories describe a low energy
limit of string theory in a background magnetic field. On
the other hand, there is no regime in which space-time
noncommutative field theory is an appropriate description of
string theory. Whenever space-time noncommutative field
theory becomes relevant massive open string states cannot be
neglected. © 2000 Elsevier Science B.V.},
Doi = {10.1016/S0550-3213(00)00525-3},
Key = {fds287688}
}
@article{fds370406,
Author = {Dai, L and Fleming, S and Hodges, R and Mehen, T},
Title = {Strong decays of Tcc+ at NLO in an effective field
theory},
Journal = {Physical Review D},
Volume = {107},
Number = {7},
Year = {2023},
Month = {April},
url = {http://dx.doi.org/10.1103/PhysRevD.107.076001},
Abstract = {The Tcc+ exotic meson, discovered by the LHCb Collaboration
in 2021, can be interpreted as a molecular state of D(∗)0
and D(∗)+ mesons. We compute next-to-leading-order (NLO)
contributions to the strong decay of Tcc+ in an effective
field theory for D mesons and pions, considering
contributions from one-pion exchange and final-state
rescattering. Corrections to the total width, as well as the
differential distribution in the invariant mass of the
final-state D-meson pair are computed. The results remain in
good agreement with LHCb experimental results when the NLO
contributions are added. The leading uncertainties in the
calculation come from terms which depend on the scattering
length and effective range in D-meson scattering.},
Doi = {10.1103/PhysRevD.107.076001},
Key = {fds370406}
}
@article{fds305711,
Author = {Mehen, T},
Title = {Summing O( β0nαsn+1)
corrections to top quark decays},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {417},
Number = {3-4},
Pages = {353-360},
Publisher = {Elsevier BV},
Year = {1998},
url = {http://dx.doi.org/10.1016/S0370-2693(97)01348-8},
Abstract = {Order β0nαsn+1 QCD corrections to top quark decays into W+
and H+ bosons are computed to all orders in perturbation
theory. Predictions for the radiative corrections to the top
quark width are compared with the estimates from BLM scale
setting procedures. The results of the summation are shown
to greatly improve understanding of higher order corrections
in the limit mW, mH → mt, where the BLM scale setting
method is known to fail. Attempts to reduce nonperturbative
error by substituting the running mass for the pole mass in
the expression for the decay are shown to fail in the limit
mW, mH → mt because of subtleties in the treatment of
phase space. © 1998 Published by Elsevier Science
B.V.},
Doi = {10.1016/S0370-2693(97)01348-8},
Key = {fds305711}
}
@article{fds359618,
Author = {Low, I and Mehen, T},
Title = {Symmetry from entanglement suppression},
Journal = {Physical Review D},
Volume = {104},
Number = {7},
Year = {2021},
Month = {October},
url = {https://arxiv.org/pdf/2104.10835.pdf},
Abstract = {Symmetry is among the most fundamental and powerful concepts
in nature, whose existence is usually taken as given,
without explanation. We explore whether symmetry can be
derived from more fundamental principles from the
perspective of quantum information. Starting with a
two-qubit system, we show there are only two minimally
entangling logic gates: the identity and the , which
interchanges the two states of the qubits. We further
demonstrate that, when viewed as an entanglement operator in
the spin-space, the -matrix in the two-body scattering of
fermions in the -wave channel is uniquely determined by
unitarity and rotational invariance to be a linear
combination of the identity and the . Realizing a minimally
entangling -matrix would give rise to global symmetries, as
exemplified in Wigner’s spin-flavor symmetry and
Schrödinger’s conformal invariance in low energy quantum
chromodynamics. For species of qubit, the identity gate is
associated with an symmetry, which is enlarged to when there
is a species-universal coupling constant.},
Doi = {10.1103/PhysRevD.104.074014},
Key = {fds359618}
}
@article{fds287646,
Author = {Fleming, S and Leibovich, AK and Mehen, T and Rothstein,
IZ},
Title = {Systematics of quarkonium production at the LHC and double
parton fragmentation},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {86},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {November},
ISSN = {1550-7998},
url = {http://arxiv.org/abs/1301.3822},
Abstract = {In this paper, we discuss the systematics of quarkonium
production at the LHC. In particular, we focus on the
necessity to sum logs of the form log(Q/p ≥) and log(p
≥/m Q). We show that the former contributions are power
suppressed, while the latter, whose contribution in
fragmentation is well known, also arise in the short
distance (i.e., nonfragmentation) production mechanisms.
Though these contributions are suppressed by powers of m Q/p
≥, they can be enhanced by inverse powers of v, the
relative velocity between heavy quarks in the quarkonium. In
the limit p ≥m Q, short-distance production can be thought
of as the fragmentation of a pair of partons (i.e., the
heavy quark and antiquark) into the final state quarkonium.
We derive an all-order factorization theorem for this
process in terms of double parton fragmentation functions
and calculate the one-loop anomalous dimension matrix for
the double parton fragmentation functions. © 2012 American
Physical Society.},
Doi = {10.1103/PhysRevD.86.094012},
Key = {fds287646}
}
@article{fds361806,
Author = {Fleming, S and Hodges, R and Mehen, T},
Title = {Tcc+ decays: Differential spectra and two-body final
states},
Journal = {Physical Review D},
Volume = {104},
Number = {11},
Year = {2021},
Month = {December},
url = {https://arxiv.org/pdf/2109.02188.pdf},
Abstract = {The recently discovered tetraquark, Tcc+, has quark content
ccud and a mass that lies just below open charm thresholds.
Hence it is reasonable to expect the state to have a
significant molecular component. We calculate the decay of
the Tcc+ in a molecular interpretation using effective field
theory. In addition we calculate differential spectra as a
function of the invariant mass of the final state charm
meson pair. These are in good agreement with spectra
measured by LHCb. We also point out that if shallow bound
states of two pseudoscalar charm mesons exist, then two-body
decays to those bound states and a single pion or photon can
significantly enhance the width of the Tcc+.},
Doi = {10.1103/PhysRevD.104.116010},
Key = {fds361806}
}
@booklet{Mehen97,
Author = {Mehen, T},
Title = {Testing quarkonium production with photoproduced [Formula
presented]},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {55},
Number = {7},
Pages = {4338-4343},
Publisher = {American Physical Society (APS)},
Year = {1997},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevD.55.4338},
Abstract = {I compute the leading color-octet contributions to the
process [Formula presented] within the nonrelativistic QCD
(NRQCD) factorization formalism. In the color-singlet model,
[Formula presented] can only be produced when the photon
interacts through its structure function, while the
color-octet mechanism allows for production of [Formula
presented] via direct photon-gluon fusion. Resolved photon
processes can be distinguished easily from direct photon
processes by examining the fraction of the incident photon
energy carried away by the [Formula presented] in the event.
Therefore, this process provides a conclusive test of the
color-octet mechanism. [Formula presented] production is
particularly sensitive to the NRQCD matrix element which
figures prominently in the fragmentation production of
[Formula presented] at large [Formula presented] in hadron
colliders. I also examine the predictions of the color
evaporation model (CEM) of quarkonium production and find
that this process can easily discriminate between the NRQCD
factorization formalism and the CEM. © 1997 The American
Physical Society.},
Doi = {10.1103/PhysRevD.55.4338},
Key = {Mehen97}
}
@article{fds287648,
Author = {Fleming, S and Mehen, T},
Title = {The decay of the X(3872) into &chicJ and the Operator
Product Expansion in XEFT},
Journal = {Phys.Rev. D85:014016},
Year = {2012},
url = {http://arxiv.org/abs/1110.0265},
Key = {fds287648}
}
@article{fds3887,
Author = {E. Braaten and Yu Jia and T. Mehen},
Title = {The Leading Particle Effect From Heavy-Quark
Recombination},
Journal = {Phys. Rev. Lett. 89, 122002},
Year = {2002},
url = {http://arxiv.org/abs/hep-ph/0205149},
Abstract = {The leading particle effect in charm hadroproduction is an
enhancement of the cross section for a charmed hadron D in
the forward direction of the beam when the beam hadron has a
valence parton in common with the D. The large D+/D-
asymmetry observed by the E791 experiment is an example of
this phenomenon. We show that the heavy-quark recombination
mechanism provides an economical explanation for this
effect. In particular, the D+/D- asymmetry can be fit
reasonably well using a single parameter whose value is
consistent with a recent determination from charm
photoproduction.},
Key = {fds3887}
}
@article{fds287684,
Author = {Fleming, S and Mehen, T and Stewart, IW},
Title = {The NN Scattering $^3S_1-{}^3D_1$ Mixing Angle at
NNLO},
Journal = {Phys. Rev. C},
Volume = {61},
Number = {4},
Pages = {044005},
Year = {2000},
Abstract = {The 3S1-3D1 mixing angle for nucleon-nucleon scattering,
epsilon_1, is calculated to next-to-next-to-leading order in
an effective field theory with perturbative pions. Without
pions, the low energy theory fits the observed epsilon_1
well for momenta less than $\sim 50$ MeV. Including pions
perturbatively significantly improves the agreement with
data for momenta up to $\sim 150$ MeV with one less
parameter. Furthermore, for these momenta the accuracy of
our calculation is similar to an effective field theory
calculation in which the pion is treated non-perturbatively.
This gives phenomenological support for a perturbative
treatment of pions in low energy two-nucleon processes. We
explain why it is necessary to perform spin and isospin
traces in d dimensions when regulating divergences with
dimensional regularization in higher partial wave
amplitudes.},
Key = {fds287684}
}
@article{fds287630,
Author = {Mehen, T and Stewart, IW and Wise, MB},
Title = {The physics of the centrality dependence of elliptic
flow},
Journal = {Physics Letters, Section B: Nuclear, Elementary Particle and
High-Energy Physics},
Volume = {474},
Number = {1-2},
Pages = {27-32},
Publisher = {Elsevier BV},
Year = {2000},
Month = {February},
ISSN = {0370-2693},
url = {http://dx.doi.org/10.1016/S0370-2693(00)00017-4},
Abstract = {The centrality dependence of elliptic flow and how it is
related to the physics of expansion of the system created in
high energy nuclear collisions is discussed. Since in the
hydro limit the centrality dependence of elliptic flow is
mostly defined by the elliptic anisotropy of the overlapping
region of the colliding nuclei, and in the low density limit
by the product of the elliptic anisotropy and the
multiplicity, we argue that the centrality dependence of
elliptic flow should be a good indicator of the degree of
equilibration reached in the reaction. Then we analyze
experimental data obtained at AGS and SPS energies. The
observed difference in the centrality dependence of elliptic
flow could imply a transition from a hadronic to a partonic
nature of the system evolution. Finally we exploit the
multiplicity dependence of elliptic flow to make qualitative
predictions for RHIC and LHC. (C) 2000 Published by Elsevier
Science B.V.},
Doi = {10.1016/S0370-2693(00)00017-4},
Key = {fds287630}
}
@article{fds322008,
Author = {Bain, R and Makris, Y and Mehen, T},
Title = {Transverse momentum dependent fragmenting jet functions with
applications to quarkonium production},
Journal = {Journal of High Energy Physics},
Volume = {2016},
Number = {11},
Publisher = {Springer Nature},
Year = {2016},
Month = {November},
url = {http://dx.doi.org/10.1007/JHEP11(2016)144},
Abstract = {We introduce the transverse momentum dependent fragmenting
jet function (TMDFJF), which appears in factorization
theorems for cross sections for jets with an identified
hadron. These are functions of z, the hadron’s
longitudinal momentum fraction, and transverse momentum,
p⊥, relative to the jet axis. In the framework of
Soft-Collinear Effective Theory (SCET) we derive the TMDFJF
from both a factorized SCET cross section and the TMD
fragmentation function defined in the literature. The
TMDFJFs are factorized into distinct collinear and
soft-collinear modes by matching onto SCET+. As TMD
calculations contain rapidity divergences, both the
renormalization group (RG) and rapidity renormalization
group (RRG) must be used to provide resummed calculations
with next-to-leading-logarithm prime (NLL’) accuracy. We
apply our formalism to the production of J/ψ within jets
initiated by gluons. In this case the TMDFJF can be
calculated in terms of NRQCD (Non-relativistic quantum
chromodynamics) fragmentation functions. We find that when
the J/ψ carries a significant fraction of the jet energy,
the pT and z distributions differ for different NRQCD
production mechanisms. Another observable with
discriminating power is the average angle that the J/ψ
makes with the jet axis.},
Doi = {10.1007/JHEP11(2016)144},
Key = {fds322008}
}
@article{fds331487,
Author = {Hornig, A and Kang, D and Makris, Y and Mehen, T},
Title = {Transverse vetoes with rapidity cutoff in
SCET},
Journal = {Journal of High Energy Physics},
Volume = {2017},
Number = {12},
Publisher = {Springer Nature},
Year = {2017},
Month = {December},
url = {http://dx.doi.org/10.1007/JHEP12(2017)043},
Abstract = {We consider di-jet production in hadron collisions where a
transverse veto is imposed on radiation for
(pseudo-)rapidities in the central region only, where this
central region is defined with rapidity cutoff. For the case
where the transverse measurement (e.g., transverse energy or
min pT for jet veto) is parametrically larger relative to
the typical transverse momentum beyond the cutoff, the cross
section is insensitive to the cutoff parameter and is
factorized in terms of collinear and soft degrees of
freedom. The virtuality for these degrees of freedom is set
by the transverse measurement, as in typical
transverse-momentum dependent observables such as Drell-Yan,
Higgs production, and the event shape broadening. This paper
focuses on the other region, where the typical transverse
momentum below and beyond the cutoff is of similar size. In
this region the rapidity cutoff further resolves soft
radiation into (u)soft and soft-collinear radiation with
different rapidities but identical virtuality. This gives
rise to rapidity logarithms of the rapidity cutoff parameter
which we resum using renormalization group methods. We
factorize the cross section in this region in terms of soft
and collinear functions in the framework of soft-collinear
effective theory, then further refactorize the soft function
as a convolution of the (u)soft and soft-collinear
functions. All these functions are calculated at one-loop
order. As an example, we calculate a differential cross
section for a specific partonic channel, qq′ → qq′,
for the jet shape angularities and show that the
refactorization allows us to resum the rapidity logarithms
and significantly reduce theoretical uncertainties in the
jet shape spectrum.},
Doi = {10.1007/JHEP12(2017)043},
Key = {fds331487}
}
@article{fds287683,
Author = {Mehen, T and Stewart, IW and Wise, MB},
Title = {Wigner symmetry in the limit of large scattering
lengths},
Journal = {Physical Review Letters},
Volume = {83},
Number = {5},
Pages = {931-934},
Publisher = {American Physical Society (APS)},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevLett.83.931},
Abstract = {We note that, in the limit where the NN 1S0 and 3S1
scattering lengths, a(1S0) and a(3S1), go to infinity, the
leading terms in the effective field theory for strong NN
interactions are invariant under Wigner’s SU(4)
spin-isospin symmetry. This explains why the leading effects
of radiation pions on the S-wave NN scattering amplitudes
vanish as a(1S0) and a(3S1) go to infinity. The implications
of Wigner symmetry for NN → NN axion and γd → np are
also considered. © 1999 The American Physical
Society.},
Doi = {10.1103/PhysRevLett.83.931},
Key = {fds287683}
}
@article{fds287640,
Author = {Fleming, S and Mehen, T},
Title = {X(3872) in effective field theory},
Journal = {AIP Conference Proceedings},
Volume = {1182},
Pages = {491-494},
Publisher = {AIP},
Year = {2009},
Month = {December},
ISSN = {0094-243X},
url = {http://arXiv.org/abs/0907.4142},
Abstract = {If the X(3872) resonance is a shallow boundstate of a the
charm mesons D0D̄*0 and D*0D̄0 it can be described by an
effective theory of nonrelativistic D mesons coupled to
nonrelativistic pions (X-EFT). In this talk, I give a brief
overview of the X(3872), followed by a short review of
X-EFT. I end my talk with results from calculations of the
the next-to-leading-order correction to the partial decay
width Γ[X→ D0D̄0π0], and the decay of X(3872) to P-wave
quarkonia. © 2009 American Institute of
Physics.},
Doi = {10.1063/1.3293853},
Key = {fds287640}
}
@article{fds287635,
Author = {Braaten, E and Kusunoki, M and Jia, Y and Mehen, T},
Title = {[Formula Presented] asymmetry in hadroproduction from
heavy-quark recombination},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {70},
Number = {5},
Pages = {5},
Publisher = {American Physical Society (APS)},
Year = {2004},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevD.70.054021},
Abstract = {Asymmetries in the hadroproduction of charm particles
directly probe power corrections to the QCD factorization
theorems. In this paper, the heavy-quark recombination
mechanism, a power correction that explains charm meson
asymmetries, is extended to charm baryons. In this
mechanism, a light quark participates in the hard-scattering
that creates a charm quark and they hadronize together into
a charm baryon. This provides a natural and economical
explanation for the [Formula Presented] asymmetries measured
in [Formula Presented] and [Formula Presented] collisions.
© 2004 The American Physical Society.},
Doi = {10.1103/PhysRevD.70.054021},
Key = {fds287635}
}
%% Papers Accepted
@article{fds225631,
Author = {Thomas Mehen},
Title = {Exotic Quarkonium Spectroscopy: X(3872) Z(10610) Z(10650) in
Non-Relativistic Effective Theory},
Journal = {Conference Proeceedings for PhiPsi 2013, Rome, Italy,
September 11, 2013},
Year = {2013},
Key = {fds225631}
}
%% Papers Submitted
@article{fds368946,
Author = {Q. Liu and I. Low and T. Mehen},
Title = {Minimal Entanglement and Emergent Symmetries in Low-energy
QCD},
Journal = {submitted to Physics. Rev. C},
Year = {2022},
Month = {October},
url = {https://inspirehep.net/literature/2169094},
Abstract = {We study low-energy scattering of spin-1/2 baryons from the
perspective of quantum information science, focusing on the
correlation between entanglement minimization and the
appearance of accidental symmetries. The baryon transforms
as an octet under the SU(3) flavor symmetry and its
interactions below the pion threshold are described by
contact operators in an effective field theory (EFT) of QCD.
Despite there being 64 channels in the 2-to-2 scattering,
only 6 independent operators in the EFT are predicted by
SU(3). We show that successive entanglement minimization in
SU(3)-symmetric channels are correlated with increasingly
large emergent symmetries in the EFT. In particular, we
identify scattering channels whose entanglement suppression
are indicative of emergent SU(6), SO(8), SU(8) and SU(16)
symmetries. We also observe the appearance of
non-relativistic conformal invariance in channels with
unnaturally large scattering lengths. Improved precision
from lattice simulations could help determine the degree of
entanglement suppression, and consequently the amount of
accidental symmetry, in low-energy QCD.},
Key = {fds368946}
}
@article{fds375044,
Author = {M. Copeland and S. Fleming and R. Gupta and R. Hodges and T.
Mehen},
Title = {Polarized J/ψ production in semi-inclusive DIS at large
Q^2: Comparing quark fragmentation and photon-gluon
fusion},
Journal = {submitted to Phys. Rev. D},
Year = {2023},
url = {https://inspirehep.net/literature/2713399},
Key = {fds375044}
}
@article{fds348005,
Author = {Lin Dai and Feng-Kun Guo and Thomas Mehen},
Title = {Revisiting $X(3872) \to D^0 \bar{D}^0 \pi^0$ in
XEFT},
Journal = {submitted to Physical Review D},
Year = {2019},
url = {http://arxiv.org/abs/arXiv:1912.04317},
Abstract = {The calculation of the decay $},
Key = {fds348005}
}
%% Other
@misc{fds375047,
Author = {D. Beck and et. al.},
Title = {Quantum Information Science and Technology for Nuclear
Physics. Input into U.S. Long-Range Planning,
2023},
Year = {2023},
url = {https://inspirehep.net/literature/2637668},
Key = {fds375047}
}