Jet Drift in Heavy-Ion Collision: Acoplanarity and v₂

¹ Department of Physics, New Mexico State University, Las Cruces, NM 88003, USA
² Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

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Published online: 5 November 2025

Abstract

We introduce a sub-eikonal anisotropic contribution to jet-broadening, “jet drift,” that couples to the flow of the nuclear medium, showing that this effect results in a deflection of hard partons, and thus jets, in the direction of the medium flow. We study two-jet observables, i.e. v₂ and acoplanarity for √s = 5.02 TeV PbPb collisions at the LHC. We show that jet drift leads to an enhancement of the elliptic flow (v₂) of charged hadrons and modification of the acoplanarity of dihadrons and discuss the implications for jet substructure and medium response effects. We also demonstrate that we can obtain independent information about the event geometry encoded in the drift modification to acoplanarity vs v₂ enhancement, whereas the temperature dependence of these observables is qualitatively different. By disentangling this temperature vs geometry dependence of these observables, we can add discriminatory power to our analysis. Next, we study acoplanarity and v₂ across different system sizes and collisional energies i.e. 200 GeV AuAu collision at RHIC using our in-house simulation package (APE). Our analysis will be critical for understanding and generalizing dynamical jet-QGP interactions for different collisional systems and energies which will aid event engineering applications in the future.