The SU(2) and SU(3) chiral phase transitions within Chiral Perturbation Theory

Abstract

The SU(2) and SU(3) chiral phase transitions in a hot gas made of pions, kaons and etas are studied within the framework of Chiral Perturbation Theory. By using the meson meson scattering phase shifts in a second order virial expansion, we are able to describe the temperature dependence of the quark condensates. We have estimated the critical temperatures where the different condensates melt. In particular, the SU(3) formalism yields a lower critical temperature for the non-strange condensates than within SU(2), and also suggests that the strange condensate may melt at a somewhat higher temperature, due to the different strange and non-strange quark masses.

4 pages, two figures. Final version to appear in Phys Rev D. Complete model independent calculation. Unitarized ChPt only used to check extrapolation at high T. References added and numerical bug corrected