EPJ Web of Conferences 316, 02002 (2025)
https://doi.org/10.1051/epjconf/202531602002

Diffusion of heavy quarks in the early stage of high-energy nuclear collisions

¹ Department of Physics, University of Jyväskylä, P.O. Box 35, 40014 University of Jyväskylä, Finland
² School of Physical Sciences, Indian Institute of Technology Goa, Ponda - 403401, Goa, India
³ Department of Physics and Astronomy "Ettore Majorana", University of Catania, Via S. Sofia 64, I-95123 Catania, Italy
⁴ INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania, Italy
⁵ INFN-Sezione di Catania, Via S. Sofia 64, I-95123 Catania, Italy

^* e-mail: pooja19221102@iitgoa.ac.in
^** e-mail: santosh@iitgoa.ac.in
^*** e-mail: greco@lns.infn.it
^**** e-mail: marco.ruggieri@dfa.unict.it

Published online: 27 January 2025

Abstract

We study the diffusion of heavy quarks in the early stage of highenergy nuclear collisions. The pre-equilibrium stage of relativistic heavy-ion collisions, commonly known as Glasma, evolves according to the classical Yang-Mills equations. Heavy quarks are coupled to the evolving Glasma fields via relativistic kinetic theory. We compute the momentum broadening, σ_p as well as the angular momentum fluctuations of heavy quarks in the early stage, which turn out to be anisotropic due to the anisotropy of the background gluon fields. We observe that σ_p ∝ t² at very initial times. This non-Markovian diffusion of heavy quarks in the early stages is explained by the memory effect present in the gluon fields.