Consistent Determination of Particle Production in p-A, d-A and A-A Collisions using Color Glass Condensate

TL;DR

This paper develops an improved Color Glass Condensate model to accurately predict particle production in various nuclear collisions, highlighting its implications for understanding initial conditions and multiplicity at high energies.

Contribution

An improved, self-consistent CGC model that better describes rapidity distributions across different collision systems and energies, with specific predictions for LHC Pb+Pb collisions.

Findings

The model accurately fits bulk rapidity distributions across systems.

It predicts lower particle multiplicities at LHC energies.

Predictions align with simple extrapolations used by PHOBOS.

Abstract

The success of nonviscous hydrodynamics in describing the collective flow properties of bulk low $p_\perp$ observables at RHIC has led to the claim that a novel form of {\it strongly coupled} Quark Gluon Plasma (sQGP) is created in 200 AGeV Au+Au collisions. This success depends strongly, however, on the initial conditions assumed in the calculations. In particular, agreement with data is only obtained assuming Glauber nuclear reaction plane (participant) geometry. The KLN model of Color Glass Condenstate (CGC) initial conditions require the existence of nonvanishing viscous effects. We develop an improved model of CGC that is more internally consistent between the central and diffuse edge regions. The improved model is shown to describe bulk rapidity distributions for a wide assortment of system sizes, geometries and energies. The self consistency forces a specific $\sqrt{s}$ dependence of the multiplicity which leads to surprisingly low particle production predictions for Pb+Pb collisions at LHC COM energies. These predictions are similar to those made using simple linear extrapolations of multiplicity attempted by the PHOBOS collaboration.