Jet evolution in a dense QCD medium

Abstract

To probe the properties of the quark-gluon plasma created in heavy-ion collisions, a very useful class of observables refers to the propagation of energetic jets. A jet is a collimated spray of particles generated via successive parton branchings, starting with a virtual quark or gluon produced by the collision. When such a jet is produced in the dense environment of a nucleus-nucleus collision, its interactions with the surrounding medium lead to a modification of its properties, phenomenon known as jet quenching. In this thesis, we develop a new theory to describe jet quenching. We compute for the first time the effects of the medium on multiple vacuum-like emissions, that is emissions triggered by the virtuality of the initial parton. We present a new physical picture for jet evolution, with notably a factorisation in time between vacuum-like emissions and medium-induced emissions. This picture is Markovian, hence well suited for a Monte Carlo implementation that we develop in the parton shower JetMed. We then investigate the phenomenological consequences of our new picture on jet observables and especially the jet nuclear modification factor $R_{AA}$, the Soft Drop $z_g$ distribution and the jet fragmentation function. Our Monte Carlo results prove to be in good agreement with the LHC measurements.

Ph.D. dissertation; 278 pages

References in corpus (33)

• PYTHIA 6.4 Physics and Manual
• The order of the quantum chromodynamics transition predicted by the standard model of particle physics
• LHAPDF6: parton density access in the LHC precision era
• Glauber Modeling in High Energy Nuclear Collisions
• The equation of state in (2+1)-flavor QCD
• Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?
• Triangular flow in hydrodynamics and transport theory
• Dihadron azimuthal correlations in Au+Au collisions at sqrt(s_NN)=200 GeV
• Direct observation of dijets in central Au+Au collisions at sqrt(s_NN) = 200 GeV
• Studies of jet quenching using isolated-photon + jet correlations in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• Measurements of the Nuclear Modification Factor for Jets in Pb+Pb Collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with the ATLAS Detector
• Measurement of jet fragmentation in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• Antiangular Ordering of Gluon Radiation in QCD Media
• Sudakov Safety in Perturbative QCD
• Measurement of jet suppression in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Q-PYTHIA: a medium-modified implementation of final state radiation
• Measurement of inclusive jet charged-particle fragmentation functions in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with the ATLAS detector
• Measurement of jet fragmentation into charged particles in pp and PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• Collisional Energy Loss in a Finite Size QCD Matter
• Collisional energy loss of a fast heavy quark in a quark-gluon plasma
• Simple Formula for High-Energy Gluon Bremsstrahlung in a Finite, Expanding Medium
• Multistage Monte-Carlo simulation of jet modification in a static medium
• Mach cone induced by $\gamma$-triggered jets in high-energy heavy-ion collisions
• The QCD collisional energy loss revised
• Parton model description of multiparticle azimuthal correlations in $pA$ collisions
• Jet Shapes in Opaque Media
• Decomposing transverse momentum balance contributions for quenched jets in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• Angular distribution of medium-induced QCD cascades
• Relating the description of gluon production in pA collisions and parton energy loss in AA collisions
• The Jet Shape at NLL${}^{\prime }$
• Radiative corrections to the jet quenching parameter in dilute and dense media
• The JETSCAPE framework
• The in-medium scale evolution in jet modification