Vector and axialvector mesons at nonzero temperature within a gauged linear sigma model

We consider vector and axialvector mesons in the framework of a gauged linear sigma model with chiral $U(N_f)_R \times U(N_f)_L$ symmetry. For $N_f=2$, we investigate the behavior of the chiral condensate and the meson masses as a function of temperature by solving a system of coupled Dyson-Schwinger equations derived via the 2PI formalism in double-bubble approximation. We find that the inclusion of vector and axialvector mesons tends to sharpen the chiral transition. Within our approximation scheme, the mass of the $\rho$ meson increases by about 100 MeV towards the chiral transition.