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Toward An Analysis of Direct Photons in Pb-Pb Collisions at $\sqrt{s_{NN}}$ = 5.02 TeV in the ALICE experiment

ORAL

Abstract

Usually quarks and gluons are confined to hadrons and cannot be directly observed. But under extreme temperatures and pressure, Quantum Chromodynamics (QCD) predicts a phase transition from normal hadronic matter to one in which color charges can flow freely. This deconfined partonic state, referred to as the Quark Gluon Plasma (QGP), holds a wealth of interesting information and a full understanding of the QGP is a major objective in the experimental research program at the Large Hadron Collider (LHC). Our analysis will be specifically focused on direct photons, defined as photons not originating from hadronic decays. Unlike hadrons, these photons are produced at all stages of the collision and escape from hot nuclear matter virtually unaffected. This is because photons are colorless and therefore have a mean free path greater than the size of the created fireball. These photons are therefore sensitive to information on the initial temperature and space-time evolution of the thermalized medium created in heavy-ion collisions. Their dynamics, however, are not fully understood, and a more complete understanding of their properties will significantly further our understanding of the Quark-Gluon Plasma as a whole. In this talk, we will present progress towards extracting results on direct photons within and outside of jets from $\sqrt{s_{NN}}$ = 5.02 TeV Pb-Pb collisions recorded at ALICE in 2018. These photons are identified via the photon conversion method, along with a jet-finder, allowing us to study the association of low momentum photons with reconstructed jets.

Presenters

  • Evan Craft

    Yale University

Authors

  • Evan Craft

    Yale University