Finite temperature pion vector form factors in chiral perturbation theory

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≃150 MeV. These results point in the direction suggested by many analysis of dilepton production data in relativistic heavy ion collisions.