[Submitted on 16 Jan 2026] (cross-list from hep-ph)
Elliptic flow of charm quarks produced in the early stage of pA collisions
Gabriele Parisi🇮🇹 · Fabrizio Murgana🇫🇷 · Vincenzo Greco🇮🇹 · Marco Ruggieri🇮🇹
We investigate the build-up of elliptic flow of charm quarks produced in the early pre-equilibrium stage of high-energy proton--nucleus collisions. The initial stage is modeled within the Color Glass Condensate framework as an evolving glasma, initialized through the McLerran--Venugopalan model. Subnucleonic fluctuations have been implemented as constituent-quark hotspots for both the proton and the nuclear participants. Charm quarks are propagated in the evolving non-Abelian background by solving the relativistic Wong equations for their coordinates, momenta, and color charges. First, we compute the nuclear modification factor of charm quarks, finding a slight migration towards higher states in agreement with previous results in the literature. Then, we focus on the azimuthal anisotropies acquired through the interaction with glasma fields. We find that glasma-induced momentum anisotropies are efficiently transmitted to heavy quarks within , leading to a sizeable charm-quark , with a magnitude that increases with the strength of the initial fields and with the number of nuclear participants. Remarkably, we show that the early-stage contribution alone can account for a significant fraction of the experimentally observed elliptic flow in p-Pb collisions, indicating that pre-hydrodynamic dynamics can play a non-negligible role in the final-state heavy-flavor collectivity, especially in small systems.
- Comments:
- 12 pages, 9 figures. v2: added reference to Zenodo repository, minor revisions to match the version published in Phys. Rev. D
- Subjects:
- High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
- arXiv:
- 2601.11123 [pdf]