Heavy Quarks in the initial stages of Proton-Ion Collisions

TL;DR

This paper investigates the initial gluon-dominated phase of proton-ion collisions, called glasma, and its significant effects on heavy quark dynamics, including dissociation and momentum anisotropy transfer, with implications for understanding QCD matter.

Contribution

It provides a detailed analysis of how intense gluon fields in the early stages influence heavy quark behavior and introduces new insights into non-boost invariant medium fluctuations.

Findings

50% dissociation rate of quark-antiquark pairs due to glasma

Large momentum anisotropy transfer to heavy quarks

Rapidity fluctuations do not cause significant isotropization within glasma timescales

Abstract

Collisions among heavy ions, like Pb or Au, are a great tool to study the theory of strong interactions, that is Quantum Chromodynamics (QCD). In particular, these experiments are able to give insights on all the complex phases of matter that the theory of QCD allows. In this PhD Thesis we have investigated the initial stages of proton-ion collisions: in particular, we will focus on the first $\sim 0.4$ fm/c ($\sim 10^{-24}$ s) after the collision, which are dominated by very intense gluon fields, in a state called glasma. We investigated the effect of such fields on the dynamics of heavy quarks (charm and beauty) which are created and evolve in this medium. The effect of the initial gluon fields on heavy quarks is quite substantial, in particular we observe that the glasma provokes a $50\%$ dissociation rate on quark-antiquark pairs. Moreover, glasma fields have a large momentum anisotropy, and transmit a large part of such anisotropy to the heavy quarks which evolve in this medium. Finally, we have generalized our study to a non-boost invariant medium, and shown that fluctuations in rapidity do not lead to significant isotropization within glasma timescales.