Finite temperature pion vector form factors in Chiral Perturbation Theory

Abstract

We discuss the thermal behaviour of the pion vector form factors and calculate them in one-loop Chiral Perturbation Theory. The perturbative result is used to analyze the $T$-dependent electromagnetic pion charge radius, obtaining a rough estimate of the deconfinement critical temperature. Imposing thermal unitarity, we generate the $ρ$ resonance pole for the form factor in the center of mass frame. The $ρ$ peak height in the modulus of the form factor decreases for increasing temperature, while its width increases and the peak position is slightly shifted downwards for $T\simeq$ 150 MeV. These results point in the direction suggested by many analysis of dilepton production data in relativistic heavy ion collisions.

15 pages, 4 figures, final version to appear in Phys.Lett.B, added references and comments, abstract changed