Speaker
Description
Lattice QCD results for the magnetic susceptibility of the medium just below the cross-over temperature are difficult to be reproduced by the available hadronic models. In particular, the widely used hadron resonance gas, remarkably successful to describe numerous other lattice results, is substantially too strong diamagnetic as compared to the data, at all temperatures available in the lattice simulations, starting at low temperature $T\sim130$ MeV. We propose a possible approach with quark-meson model where the quark masses are fixed from baryon-baryon and baryon-strangeness susceptibility data in order to be consistent. We show that the quark-meson model can reproduce the lattice data for magnetic susceptibility, generating the lacking paramagnetism in HRG, provided its vacuum contribution is treated carefully. The fitted quark masses are consistent with other model results e.g quasi-particle picture. We also compute the contribution of the pion-vector meson loops in the evaluation of the magnetic susceptibility via the photon polarization, showing it is small.
