Conical Flow from Quenched Jets in sQGP

Abstract

Starting with a reminder of what is strongly coupled Quark-Gluon Plasma (sQGP), we proceed to recent advances in jet quenching and heavy quark diffusion, with a brief summary of various results based on AdS/CFT correspondence. The conical flow is a hydrodynamical phenomenon created by energy and entropy deposited by high energy jets propagating in matter, similar in nature to well known sonic boom from the supersonic planes. After a brief review, we discuss excitations of two hydro modes -sound and "diffusion" -which can be excited in this way. We also study expanding matter case, with a variable speed of sound, and use adiabatic invariants to show that the parameter v/T (v velocity in the wave, T temperature) is increasing, up to a factor 3, during expansion. At the end we discuss recent results of the Princeton group which derived conical flow from AdS/CFT. Why do we think that QGP is strongly coupled?A realization [1-3] that QGP at RHIC is a strongly coupled liquid has led to a paradigm shift in the field. It was extensively debated at the "discovery" BNL workshop in 2004 [4] (at which the abbreviation sQGP was established) and multiple other meetings since. In the intervening three years we all had to learn a lot, in part from the branches of physics which happened to have experience with strongly coupled systems. Those range from quantum gases to classical plasmas to string theory. In short, there seem to be not one but actually two difficult issues we are facing. One is to understand why QGP at T ∼ 2T c is strongly coupled, and what exactly it means. The second large problem is to understand what happens at the deconfinement, at |T − T c | T c , which may be a key to the famous confinement problem.As usual, progress proceeds from catching/formulating the main concepts and qualitative pictures, to mastering technical tools, to final quantitative predictions: and now we are somewhere in the middle of this process. The work is Nuclear Physics A 783 (2007) 39c-56c 0375-9474/$ -see front matter

Energy loss of gluons, baryons andk-quarks in an Script N = 4 SYM plasma

“…In interesting followup work, the authors of [28,29,30] studied the profile of the coherent gluonic fields set up by the joint quark-plasma system, which are responsible for taking energy away from the moving quark. Their results appear to be consistent with phenomenological expectations of 'conical flow' [31].…”

“…In interesting followup work, the authors of [28,29,30] studied the profile of the coherent gluonic fields set up by the joint quark-plasma system, which are responsible for taking energy away from the moving quark. Their results appear to be consistent with phenomenological expectations of 'conical flow' [31].An important measure of energy loss used in phenomenological models of mediuminduced radiation (for reviews see [32]) is the jet-quenching parameterq, defined as the average squared transverse momentum transferred to the quark by the medium, per unit distance travelled. The authors of [33] suggested thatq could be identified with the logarithm of a certain lightlike Wilson loop, 3 and then used AdS/CFT to compute the latter for N = 4 SYM.…”

Stress-energy tensor of a quark moving through a strongly-coupledN=4supersymmetric Yang-Mills plasma: Comparing hydrodynamics and AdS/CFT duality

“…We note however, that in the large N c limit 21) with no additional derivative corrections. This follows from the fact that the linearized hydrodynamic expressions for the conserved densities ∆T 0ν hydro , as given in Eqs.…”

“…Analysis of the distribution and correlations in produced jets can provide information about the dynamics of the plasma, including the rates of energy loss and momentum broadening of quarks traversing the plasma [21,22,23].…”

Light quark energy loss in strongly coupledN=4supersymmetric Yang-Mills plasma

“…(See, for example, Refs. [12,13,14,15,16,17,18,19,20,21,22,23,24,25], and references therein.) At least for some quantities, this is quite successful.…”