Initial energy density and gluon distribution from the glasma in heavy-ion collisions

Hirotsugu Fujii, Kenji Fukushima, and Yoshimasa Hidaka

Phys. Rev. C 79, 024909 – Published 27 February 2009

Abstract

We estimate the energy density and the gluon distribution associated with the classical fields describing the early-time dynamics of heavy-ion collisions. In the McLerran-Venugopalan model, we first decompose the energy density into the momentum components exactly, with the use of the Wilson line correlators. Then we evolve the energy density with the free-field equation, which is justified by the dominance of the ultraviolet modes near the collision point. We also discuss the improvement that occurs with the inclusion of nonlinear terms into the time evolution. Our numerical results at RHIC energy are fairly consistent with the empirical values.