Probing the Gluon Plasma with Charm Balance Functions

TL;DR

This paper proposes using charm balance functions to investigate a hypothesized long-lived gluon plasma phase in heavy-ion collisions, aiming to understand early gluon dynamics before quark chemical equilibrium is reached.

Contribution

It introduces charm balance functions as a novel method to probe the existence and properties of a gluon-dominated phase prior to quark-gluon plasma formation.

Findings

Charm quarks can probe early gluon dynamics.

Charm balance functions can distinguish gluon plasma signatures.

The scenario suggests a long-lived gluon phase affects charm correlations.

Abstract

Recent theoretical explanations for how hydrodynamic-like flow can build up quickly in small collision systems (hydrodynamization) has led to a microscopic picture of flow building up in a gluon-dominated phase before chemical equilibrium between quarks and gluons has been attained. The goal of this contribution to Offshell-2021 is to explore consequence of assuming a long-lived gluon-dominated phase, which we shall denote a gluon plasma (GP). As these consequences are naturally enhanced in a large systems, we assume and explore the extreme scenario in which a GP would be created in AA collisions and exist for significant time before the formation of a chemically-equilibrated quark-gluon plasma (QGP). The GP and its formation would be impossible to probe with light-quark hadrons, which are first produced later in this scenario. As charm quarks are produced early in the collision, they can circumvent the limitations of light quarks and we propose charm balance functions as an effective tool to test this idea and constrain the dynamics of the GP.