Publications [#245705] of Shailesh Chandrasekharan

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Papers Published
  1. Cecile, DJ; Chandrasekharan, S, Role of the σ resonance in determining the convergence of chiral perturbation theory, Physical Review D - Particles, Fields, Gravitation, and Cosmology, vol. 77 no. 9 (2008), pp. 091501 [PhysRevD.77.091501], [doi] .

    Abstract:
    The dimensionless parameter ξ=Mπ2/(16π2Fπ2), where Fπ is the pion decay constant and Mπ is the pion mass, is expected to control the convergence of chiral perturbation theory applicable to QCD. Here we demonstrate that a strongly coupled lattice gauge theory model with the same symmetries as two-flavor QCD but with a much lighter σ-resonance is different. We first confirm that the leading low-energy constants appearing in the chiral Lagrangian are the same when calculated from the p-regime and the -regime as expected. However, ξ 0.002 is necessary before 1-loop chiral perturbation theory predicts the data within 1%. For ξ>0.0035 the data begin to deviate dramatically from 1-loop chiral perturbation theory predictions. We argue that this qualitative change is due to the presence of a light σ-resonance in our model. Our findings may be useful for lattice QCD studies. © 2008 The American Physical Society.