Correlations of High-pT Hadrons and Jets in ALICE

Filip Krizek

doi:10.3390/universe5050124

Abstract

There are two prominent experimental signatures of quark–gluon plasma creation in ultra-relativistic heavy-ion collisions: the jet quenching phenomenon and the azimuthal-momentum space-anisotropy of final-state particle emission. Recently, the latter signature was also observed in lighter collision systems such as p–Pb or pp. This raises a natural question of whether in these systems, the observed collectivity is also accompanied by jet quenching. In this paper, we overview ALICE measurements of the jet quenching phenomenon studied using semi-inclusive distributions of track-based jets recoiling from a high-transverse momentum ( p T ) hadron trigger in Pb–Pb and p–Pb collisions at LHC energies. The constructed coincidence observable, the per trigger normalized yield of associated recoil jets, is corrected for the complex uncorrelated jet background, including multi-partonic interactions, using a data-driven statistical subtraction method. In the p–Pb data, the observable was measured in events with different underlying event activity and was utilized to set an upper limit on the average medium-induced out-of-cone energy transport for jets with resolution parameter R = 0.4 . The associated jet momentum shift was found to be less than 0.4 GeV/c at 90% confidence.

Highlights

Ultra-relativistic heavy-ion collisions are used to probe the properties of strongly interacting matter in the regime of extremely high-energy densities and temperatures and vanishing baryochemical potential [1]
Lattice quantum chromodynamics calculations predict that under such conditions, the hadron gas phase undergoes a transition to the state called quark–gluon plasma (QGP) [2]
Among different experimental observables that are studied in this context, two of them are believed to be directly associated with the production of the QGP in heavy-ion collisions: the large azimuthal-momentum space-anisotropy of produced particles [4,5] and the jet quenching phenomenon [6,7]

Summary

Introduction

Ultra-relativistic heavy-ion collisions are used to probe the properties of strongly interacting matter in the regime of extremely high-energy densities and temperatures and vanishing baryochemical potential [1]. Among different experimental observables that are studied in this context, two of them are believed to be directly associated with the production of the QGP in heavy-ion collisions: the large azimuthal-momentum space-anisotropy of produced particles [4,5] and the jet quenching phenomenon [6,7]. The jet quenching phenomenon is manifested by a marked reduction of energy of high-pT hadrons and jets that traversed the QGP medium. Their yield measured in heavy-ion collisions is suppressed. In heavy-ion collisions, highly virtual partons that fragment to jets are produced by hard scatterings that happen before the QGP is formed. It is suitable for jets having large R and low pT

Hadron-Jet Coincidence Measurements in Pb–Pb Collisions at

Findings

Searches for Jet Quenching in p–Pb Collisions at