The SU(2) and SU(3) chiral phase transitions within chiral perturbation theory

The SU(2) and SU(3) chiral phase transitions in a gas made of pions, kaons, and etas are studied within the framework of chiral perturbation theory. We describe the temperature dependence of the quark condensates by using the meson meson scattering phase shifts in a second order virial expansion. In particular, the SU(3) formalism yields a somewhat lower melting temperature for the nonstrange condensates than within SU(2), and also predicts that the strange condensate melting is slower than that of the nonstrange, due to the different strange and nonstrange quark masses.