Vacuum creation of quarks at the time scale of QGP thermalization and strangeness enhancement in heavy-ion collisions

The vacuum parton creation in quickly varying external fields is studied at the time scale of order 1 fm/$c$ typical for the quark-gluon plasma formation and thermalization. To describe the pre-equilibrium evolution of the system the transport kinetic equation is employed. It is shown that the dynamics of production process at times comparable with particle inverse masses can deviate considerably from that based on classical Schwinger-like estimates for homogeneous and constant fields. One of the effects caused by non-stationary chromoelectric fields is the enhancement of the yield of $s\bar{s}$ quark pairs. Dependence of this effect on the shape and duration of the field pulse is studied together with the influence of string fusion and reduction of quark masses.