Correlations in the Monte Carlo Glauber model

TL;DR

This paper examines the correlations between sources in the Monte Carlo Glauber model for proton-nucleus and nucleus-nucleus collisions, revealing that these correlations have modest effects on fluctuations at RHIC and LHC energies.

Contribution

It provides a detailed analysis of source correlations, including nucleon-nucleon and twin correlations, within the Glauber model framework.

Findings

Correlations have modest effects on size and eccentricity fluctuations.

The Glauber model effectively treats sources as approximately independent.

Twin correlations are identified as a new phenomenon in collision modeling.

Abstract

Event-by-event fluctuations of observables are often modeled using the Monte Carlo Glauber model, in which the energy is initially deposited in sources associated with wounded nucleons. In this paper, we analyze in detail the correlations between these sources in proton-nucleus and nucleus-nucleus collisions. There are correlations arising from nucleon-nucleon correlations within each nucleus, and correlations due to the collision mechanism, which we dub twin correlations. We investigate this new phenomenon in detail. At the RHIC and LHC energies, correlations are found to have modest effects on size and eccentricity fluctuations, such that the Glauber model produces to a good approximation a collection of independent sources.