Effective restoration of the UA(1) symmetry with temperature and density -: art. no. 116013

We investigate the full U(3)circle timesU(3) chiral symmetry restoration, at finite temperature and density, on the basis of a quark model which incorporates the most relevant properties of QCD in this context: explicit and spontaneous breaking of chiral symmetry and axial U-A(1) symmetry breaking. A specific lattice-inspired behavior of the topological susceptibility, combined with the convergence of chiral partners, signals the onset of an effective chiral symmetry restoration. The results suggest that the axial part of the symmetry is restored before the possible restoration of the full U(3)circle timesU(3) chiral symmetry can occur. This conclusion is valid in the context of both finite temperature and density.