Viscosity and thermal conductivity effects at first-order phase transitions in heavy-ion collisions

Effects of viscosity and thermal conductivity on the dynamics of first-order phase transitions are studied. The nuclear gas-liquid and hadron-quark transitions in heavy-ion collisions are considered. We demonstrate that at non-zero thermal conductivity, $\kappa \neq 0$, onset of spinodal instabilities occurs on an isothermal spinodal line, whereas for $\kappa =0$ instabilities take place at lower temperatures, on an adiabatic spinodal.Comment: invited talk at 6th International Workshop on Critical Point and Onset of Deconfinment (CPOD2010), Dubna, August 22-28, 201

Enhanced heavy quark-pair production in strong SU(2) color field

Non-perturbative charm and bottom quark-pair production is investigated in the early stage of heavy ion collisions. Following our earlier works, the time-dependent study is based on a kinetic description of fermion-pair production in strong non-Abelian fields. We introduce time-dependent chromo-electric external field with a pulse-like time evolution, which simulates the overlap of two colliding heavy ions. The calculations is performed in a SU(2) color model with finite current quark masses. Yields of heavy quark-pairs are compared to the ones of light and strange quark-pairs. We show that the small inverse duration time of the field pulse determines the efficiency of the quark-pair production. Thus we do not see the expected suppression for heavy quark production, as follows from the Schwinger formula for constant field, but rather an enhanced heavy quark production at ultrarelativistic energies. We convert pulse duration time-dependent results into collisional energy dependence and introduce flavour-dependent energy string tensions, which can be used in string based model calculations at RHIC and LHC energies.Comment: 11 pages, 9 figure

Thermal conductivity in dynamics of first-order phase transition

Effects of thermal conductivity on the dynamics of first-order phase transitions are studied. Important consequences of a difference of the isothermal and adiabatic spinodal regions are discussed. We demonstrate that in hydrodynamical calculations at non-zero thermal conductivity, $\kappa \neq 0$, onset of the spinodal instability occurs, when the system trajectory crosses the isothermal spinodal line. Only for $\kappa = 0$ it occurs at a cross of the adiabatic spinodal line. Therefore ideal hydrodynamics is not suited for an appropriate description of first-order phase transitions.Comment: 21 pages, 2 figures; submitted to Nuclear Physics A on 26 Feb 201