Aharony, O; Gomis, J; Mehen, T, *On Theories with Lightlike Noncommutativity*,
JHEP, vol. 9 no. 9 PART A
(2000),
pp. 23 .
**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.*