Non-equilibrium quark-gluon plasma at the initial stage of ultrarelativistic heavy-ion collisions

Abstract

There are discussed unstable plasma modes and screening lengths in the many-parton system created due to hard and semihard processes at the initial stage of ultrarelativistic heavy-ion collisions. Hard and semihard processes are expected to lead to a copious production of partons, mainly gluons, in ultrarelativistic heavy-ion collisions [1–8]. The number of gluons generated at the initial stage of central Au-Au collision is estimated [6] as 570 at RHIC and 8100 at LHC. Since the longitudinal momenta of the produced partons are, in average, much greater than the transverse momenta, one expects instability of such a many-parton system due to specific plasma modes. Using the Penrose criterion [9] we discuss the stability conditions and then we find explicitly the unstable mode. In the second part of this note we consider screening of the chromoelectric field in the many-parton system.