Geometric bias and centrality dependence of jet quenching in high-energy nuclear collisions

TL;DR

This paper introduces a geometric bias model based on impact parameter dependence in initial conditions, combined with a transport model, to explain the centrality dependence of jet quenching in high-energy nuclear collisions.

Contribution

The study develops a HIJING-based initial condition model that incorporates impact parameter dependence, addressing suppression in peripheral collisions, and combines it with a transport model for improved jet quenching predictions.

Findings

The model reproduces the centrality dependence of charged hadron suppression in Pb+Pb collisions.

Impact parameter dependence causes a geometric bias that suppresses jet yields in peripheral collisions.

The combined approach provides a satisfactory description of experimental data at 5.02 TeV.

Abstract

Jet quenching provides a valuable measure of the opacity of the quark-gluon plasma (QGP) produced in high-energy heavy-ion collisions. However, substantial suppression of charged hadron spectra is observed in highly peripheral collisions, despite the expectation of negligible jet-QGP interactions in this regime. To address this, we develop a HIJING-based initial condition model that accounts for the impact parameter dependence of both inelastic nucleon-nucleon (NN) collisions and the number of hard partonic scatterings per inelastic NN collision. This dependence introduces a geometric bias effect on the jet yield within a given centrality class of nucleus-nucleus (AA) collisions, suppressing the high transverse momentum hadron spectrum in peripheral collisions due to dilute nucleon overlap at large AA impact parameters. By combining this improved initial condition model with a linear Boltzmann transport model for jet-QGP interactions, we obtain a satisfactory description of the centrality dependence of charged hadron suppression in Pb+Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV.