Jet Drift and Collective Flow in Heavy-Ion Collisions

TL;DR

This paper introduces the concept of jet drift in heavy-ion collisions, demonstrating how flowing quark-gluon plasma deflects high-energy jets and proposing a new observable to measure this effect through gamma-jet correlations.

Contribution

It presents the first systematic study of jet drift caused by medium flow in heavy-ion collisions and proposes a measurable observable for experimental detection.

Findings

Jet drift causes measurable deflection of jets in flowing plasma.

The effect persists despite fluctuations in collision geometry.

A new observable correlates jet acoplanarity with soft particle flow.

Abstract

We study the tomographic applications of a new phenomenon we dub "jet drift" -- the deflection of high-energy particles and jets toward the direction of a flowing medium -- to the quark-gluon plasma produced in heavy-ion collisions. While the physics of jet drift is quite general, for specificity we consider the case of photon-jet production at mid-rapidity. Beginning with the simplest possible model, a large slab of uniformly flowing plasma, we systematically introduce the geometrical elements of a heavy-ion collision in a simple optical Glauber model. We find that the moving medium causes the jet to drift in the direction of the flow, bending its trajectory and leaving detailed signatures of the flow pattern in the distribution of $\gamma + \: \mathrm{jet}$ acoplanarities. In the elliptical geometries produced in non-central collisions, this drift effect leads to a strong geometry coupling which persists despite the addition of event-by-event fluctuations in the jet production point, impact parameter, and acoplanarity. We propose a new observable to measure the jet drift effect through the correlation of $\gamma + \: \mathrm{jet}$ acoplanarities with the elliptic flow of soft particles. Preliminary estimates suggest this correlation may be studied at sPHENIX and the LHC.