Scenario for ultrarelativistic nuclear collisions: Space-time picture of quantum fluctuations and the onset of quark-gluon plasma

Abstract

We study the dynamics of quantum fluctuations which take place at the earliest stage of high-energy processes and the conditions under which the data from $e$-$p$ deep-inelastic scattering may serve as an input for computing the initial data for heavy-ion collisions at high energies. Our method is essentially based on the space-time picture of these seemingly different phenomena. We prove that the ultraviolet renormalization of the virtual loops does not bring any scale into the problem. The scale appears only in connection with the collinear cutoff in the evolution equations and is defined by the physical properties of the final state. In heavy-ion collisions the basic screening effect is due to the mass of the collective modes (plasmons) in the dense nonequilibrium quark-gluon system, which is estimated. We avoid the standard parton phenomenology and suggest a dedicated class of evolution equations which describe the dynamics of quantum fluctuations in heavy-ion collisions.