Interplay between Mach cone and radial expansion and its signal inγ-jet events

Abstract

We study the hydrodynamic response to jet quenching in expanding quark-gluon plasma (QGP) and its signal in the resulting particle distribution. The ideal hydrodynamic simulations of the γ-jet events in heavy-ion collisions are performed in a full (3 + 1)-dimensional setup. The jet-induced Mach cone and the radial expansion of the background mutually push and distort each other. As a result, the particle emission is suppressed in the direction in which the radial flow is pushed back by the Mach cone when the jet path is an off-central one. This is the direct signal of hydrodynamic response to the jet and, moreover, includes information about the jet path in the expanding QGP fluid.

Angular structure of jet quenching within a hybrid strong/weak coupling model

“…Something similar can happen at weak coupling even though the energy is initially lost by gluon radiation because these radiated gluons can experience a cascade of reinteractions that converts the energy into soft particles at large angles [150][151][152][153][154][155][156]. The effects of both transverse momentum broadening [85,86,[107][108][109] and the backreaction of the medium [95,[157][158][159][160][161][162] on jet observables have also been studied within the context of perturbative energy loss mechanisms.…”

“…It is inevitable that when a jet reconstruction algorithm is used to find and reconstruct jets in heavy ion collisions, some of the energy and momentum that is counted as part of a jet in fact comes from hadrons formed from the plasma as it freezes out, given that the plasma includes a moving heated wake that, by momentum conservation, is flowing in the same direction as the jet [95,158,[160][161][162]. Furthermore, since any background subtraction procedure involves comparing events with a jet or jets to events that do not contain jets, and since events that do not contain jets also do not contain wakes, the particles from the hadronization of the wake that end up reconstructed as part of a jet will not be removed by background subtraction.…”

“…(For studies of the nonlinear response of the plasma, see refs. [158,161,175,176]). We shall also assume that the small perturbation of the velocity and temperature of the medium translates into small perturbations to the resulting distribution of particles at all momenta.…”

Bayesian Extraction of Jet Energy Loss Distributions in Heavy-Ion Collisions

“…The study of the medium modification of fully reconstructed jets in high-energy heavy-ion collisions [11,12] can provide additional constraints on theoretical approaches to parton energy loss and the jet transport coefficient. Though a fully constructed jet contains partons both from the medium-modified jet shower and medium recoil [13][14][15][16][17][18][19][20][21], one can still define jet energy loss as the difference between the final jet energies within the jet cone in vacuum and medium originating from the same initial hard parton. While the average jet energy loss is related to both jet and bulk transport coefficients, the jet energy loss distribution should contain additional information about jet-medium interaction.…”

Interplay between collective expansion and Mach cone

“…Further details on this topic can be also found in Ref. [4]. Furthermore, we also study an event in which many mini-jets traverse the QGP medium at once.…”