Can we observe effects of early nonequilibrium dynamics using collective flow.

The rapid expansion of the fireball created in a heavy-ion collision causes strong departures from equilibrium. Such effects are especially important in the very early phase of the collision, bringing a substantial pressure asymmetry. The longitudinal pressure is much smaller than the transverse one. We investigate effects of this early stage pressure asymmetry in a kinetic model without boost-invariance. In the kinetic evolution the asymmetry results from the compettion of the longitudinal expasnion rate and th erelaxation rate. Unlike the transverse flow, the directed flow is found to be very sensitive to the equilibration rate and the pressure anisotropy. [ABSTRACT FROM AUTHOR]