In jet quenching, a hard QCD parton, before fragmenting into a jet of hadrons, deposits a fraction of its energy in the medium. As the parton moves nearly with speed of light, much greater that the speed of sound of the medium, quenching jet can generate Mach shock wave. We have examined the possibility of Mach shock wave formation due to jet quenching. Assuming that the deposited energy quickly thermalize, we simulate the hydrodynamic evolution of the QGP fluid with a quenching jet and subsequent particle production. Angular distribution of pions, averaged over all the jet trajectories, resembles 'conical flow' due to Mach shock wave formation.
However, speed of sound dependence of the simulated Mach angles are at variance with that due to shock wave formation in a static medium or in a medium with finite velocity.
The strong suppression of high-$p_T$ jets in heavy ion collisions is a result of elastic and inelastic energy loss suffered by the jet multi-prong collection of color charges that are resolved by medium interactions. Hence, quenching effects depend on the fluctuations of the jet substructure that are probed by the cone size dependence of the spectrum. In this letter, we present the first complete, analytic calculation of the inclusive $R$-dependent jet spectrum in PbPb collisions at LHC energies, including resummation of energy loss effects from hard, vacuum-like emissions occurring in the med…
Jets in the vacuum correspond to multi-parton configurations that form via a branching process sensitive to the soft and collinear divergences of QCD. In heavy-ion collisions, energy loss processes that are stimulated via interactions with the medium, affect jet observables in a profound way. Jet fragmentation factorizes into a three-stage process, involving vacuum-like emissions above the medium scale, induced emissions enhanced by the medium length and, finally, long-distance vacuum-like fragmentation. This formalism leads to a novel, non-linear resummation of jet energy loss. In this talk w…
Cone-Dependent Jet Collisional Energy Loss in Finite QCD Medium
Institute of Physics Belgrade, University of Belgrade（贝尔格莱德物理研究所，贝尔格莱德大学）；Serbian Academy of Sciences and Arts（塞尔维亚科学与艺术科学院）；Faculty of Biology, University of Belgrade（贝尔格莱德大学生物学院）
The substructure of charged jets gets modified due to the presence of the medium in heavy-ion collisions which is an indication of redistribution of energy inside the jet cone. It helps to understand the energy loss mechanisms of jets in the medium. A model dependent study of the modification of differential jet shape $(ρ(r))$ and the angularity (g) due to medium, has been performed in the most central Pb-Pb collisions at 2.76 TeV in the jet range of 20-40 GeV/c.
Impact of the energy loss spatial profile and shear viscosity to entropy density ratio for the Mach cone vs. head shock signals produced by a fast moving parton in a quark-gluon plasma
We present results of a detailed analysis of experimental data on the nuclear modification factor $R_{AA}$ and the flow coefficient $v_2$ for light hadrons from RHIC for $0.2$ TeV Au+Au collisions and from LHC for $2.76$ and $5.02$ TeV Pb+Pb, and $5.44$ TeV Xe+Xe collisions. We perform calculations within the light-cone path integral approach to induced gluon emission. We use running $α_s$ which is frozen at low momenta at some value $α_{s}^{fr}$. We find that the RHIC data support somewhat larger value of $α_{s}^{fr}$. For the $χ^2$ optimized values of $α_{s}^{fr}$, the theoretical prediction…
We perform an analytic calculation of the color fields in heavy-ion collisions by considering the collision of longitudinally extended nuclei in the dilute limit of the Color Glass Condensate effective field theory of high-energy QCD. Based on general analytic expressions for the color fields in the future light cone, we evaluate the rapidity profile of the transverse pressure within a simple specific model of the nuclear collision geometry and compare our results to 3+1D classical Yang-Mills simulations.
We study the medium modification factor $I_{pp}$ within the light-cone path integral approach to induced gluon emission. We use parametrization of the running coupling $α_s(Q,T)$ which has a plateau around $Q\sim κT$. We calculate $I_{pp}$ with no free parameters using $κ$ fitted to the LHC data on the nuclear modification factor $R_{AA}$. We find that the theoretical multiplicity dependence of the ratio $I_{pp}/\langle I_{pp}\rangle$ for $5.02$ TeV $pp$ collisions agrees reasonably with the recent preliminary data from ALICE [1].
Dynamical Density Fluctuations around QCD Critical Point Based on Dissipative Relativistic Fluid Dynamics-possible fate of Mach cone at the critical point-
