1. Łukasz Juchnowski, 2. dr hab. Dariusz Prorok - IFT

1. Nonequilibrium meson production in strong fields 2. Does the low p_T pion enhancement occur in Pb-Pb collisions at the LHC, really?

Ł.J.:I will briefly introduce a kinetic equation approach to nonequilibrium pion and sigma meson production in a time-dependent, chiral symmetry breaking field (inertial mechanism). Our investigation focuses on the low-momentum pion enhancement observed in heavy-ion collisions at CERN - LHC. In this preliminary study, we consider the inertial mechanism for nonequilibrium production of the sigma mesons and their simultaneous decay into pion pairs for two cases of sigma mass evolution. The resulting pion distribution shows a strong low-momentum enhancement. D.P.: Many data in the High Energy Physics are, in fact, sample means. It is shown that when this exact meaning of the data is taken into account and the most weakly bound states are removed from the hadron resonance gas, the acceptable fit to the whole spectra of pions, kaons and protons measured at midrapidity in central Pb-Pb collisions at $sqrt{s_{NN}} = 2.76$ TeV is obtained. Low $p_{T}$ pions and protons are reproduced simultaneously as well as $p/pi$ ratio. Additionally, correct predictions extend over lower parts of large $p_{T}$ data.