Pressure Anisotropy in Heavy Ion Collisions from Color Glass Condensate

TL;DR

This paper extends calculations of the energy-momentum tensor in heavy ion collisions within the Color Glass Condensate framework, providing all-order results for energy density and pressures including running coupling effects.

Contribution

It generalizes the McLerran-Venugopalan model calculations using a small-$\tau$ expansion, incorporating higher-order terms and running coupling effects for the first time.

Findings

Energy density decreases monotonically over time

Transverse pressure decreases monotonically over time

Longitudinal pressure starts negative and approaches zero

Abstract

We generalize calculations of the energy-momentum tensor for classical gluon fields in the McLerran-Venugopalan model using the small-$\tau$ power series expansion method. Results to all orders for the energy density and pressures are given in the leading $Q^2$ approximation and with the inclusion of running coupling effects. The energy density and transverse pressure decrease monotonically with time while the longitudinal pressure starts from a negative value and increases towards zero.