Kinetics of hydrodynamic pions in chiral perturbation theory

Abstract

We determine the kinetic coefficients of ultrasoft pions using chiral perturbation theory at finite temperature close to the chiral limit. This is used to compute the axial charge diffusion and damping coefficients in the hydrodynamic effective theory for these pion waves. We show that to provide a leading order answer for these coefficients one needs to explore the dynamics of hard, soft, and ultrasoft pion modes, which are represented microscopically by the appropriate kinetic and hydrodynamic descriptions..

Comments: 30.5 pages, 7 figures. Generalization to arbitrary number of flavors, by considering pion-pion scattering in SU(N) instead of SU(2). Explanations and extra references added. Accepted for publication in Physical Review D journal