Thermal Properties of a Hot Pion Gas beyond the Quasiparticle Approximation

Abstract

Within the Matsubara formalism we derive expressions for the pion self-energy and the two-pion propagator in a hot pion gas. These quantities are used to selfconsistently calculate the in-medium $\pi \pi$ amplitude beyond the quasiparticle approximation (QPA). The results are shown to differ significantly from QPA-based calculations. We also examine the impact of chiral constraints on the $\pi \pi$ interaction in a chirally improved version of the Jülich $\pi \pi$ model.

Comments: 12 pages LaTex (3 figures uuencoded)