QGP tomography with photon tagged jets in ALICE

TL;DR

This paper discusses using photon-tagged jets in ALICE to perform tomographic measurements of the quark-gluon plasma, aiming to understand medium modifications of jet structures in heavy ion collisions.

Contribution

It introduces a method to analyze gamma+jet events for probing the medium properties in heavy ion collisions at LHC energies.

Findings

Potential to determine jet fragmentation function modifications.

Ability to measure azimuthal misalignment between photon and jet.

Provides a way to compare medium effects in AA and pp collisions.

Abstract

$\gamma +$jet events provide a tomographic measurement of the medium formed in heavy ion collisions at LHC energies. Tagging events with a well identified high $p_{T}$ direct photon and measuring the correlation distribution of hadrons emitted oppositely to the photon, allows us to determine, with a good approximation, both the jet fragmentation function and the back-to-back azimuthal misalignement of the direct photon and the jet. Comparing these two observables measured in $pp$ collisions with the ones measured in $AA$ collisions will reveal the modifications of the jet structure induced by the medium formed in $AA$ collisions and consequently will infer the medium properties.