Mott Dissociation and Kaon to Pion Ratio in the EPNJL Model

The behaviour of pseudoscalar mesons within the SU(3) PNJL-like models is considered for finite T and . We compare the pole approximation (Breit–Wigner) with the Beth–Uhlenbeck approach. We evaluate the ratios along the phase transition line in the T – plane with constant and -dependent pion and strange quark chemical potentials. Using the model, we can show that the splitting of kaon and anti-kaon masses appears as a result of introduction of density and this explains the difference in the ratio and ratio at low and their tendency to the same value at high . A sharp “horn” effect in the ratio is explained by the enhanced pion production which can be described by occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.