743 research outputs found
MHV amplitudes at strong coupling and linearized TBA equations
The maximally helicity violating (MHV) amplitudes of super
Yang-Mills theory at strong coupling are obtained by solving auxiliary
thermodynamic Bethe ansatz (TBA) integral equations. We consider a limit where
the TBA equations are linearized for large chemical potentials and masses
therein. By solving the linearized equations, we derive analytic expansions of
the 6-point MHV amplitudes in terms of the ratio of the chemical potential
and the mass . The expansions are valid up to corrections exponentially
small in or inversely proportional to powers of . The analytic
expansions describe the amplitudes for small conformal cross-ratios of the
particle momenta in a standard basis, and interpolate the amplitudes with equal
cross-ratios and those in soft/collinear limits. The leading power corrections
are also obtained analytically. We compare the 6-point rescaled remainder
functions at strong coupling and at 2 loops for the above kinematics. They are
rather different, in contrast to other kinematic regions discussed in the
literature where they are found to be similar to each other.Comment: 41 pages, 9 figures; (v2) a reference added, typos corrected, minor
revision
Functional Relations in Solvable Lattice Models II
Reported are two applications of the functional relations (-system) among
a commuting family of row-to-row transfer matrices proposed in the previous
paper Part I. For a general simple Lie algebra , we determine the
correlation lengths of the associated massive vertex models in the
anti-ferroelectric regime and central charges of the RSOS models in two
critical regimes. The results reproduce known values or even generalize them,
demonstrating the efficiency of the -system.Comment: 55 pages, harvmac, HUTP-93/A02
The QCD spin chain S matrix
Beisert et al. have identified an integrable SU(2,2) quantum spin chain which
gives the one-loop anomalous dimensions of certain operators in large N QCD. We
derive a set of nonlinear integral equations (NLIEs) for this model, and
compute the scattering matrix of the various (in particular, magnon)
excitations.Comment: 25 pages, 1 figure; v2: references adde
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