SEMINAR
Physics of the quarkgluon plasma
upcoming:
past:

Prof. Dr. Carlo Ewerz (ITP Heidelberg & EMMI/GSI & FIAS)
AdS/CFT and its application to heavy quarks in hot plasmas
[Wednesday, July 20, 16:15 h, Physikalisches Institut, INF 226, SR 01.106]
[slides]One of the most surprising findings in string theory is the AdS/CFT correspondence (or gauge/gravity correspondence) which establishes a new holographic relation between gauge theories and gravitational theories. In particular, a strongly coupled gauge theory can be equivalently described by weakly coupled gravity in a higherdimensional space. This opens a revolutionary new way to address complicated dynamical problems in strongly coupled systems and has contributed to the discovery of universal behavior in many strongly coupled quantum systems. In this talk I will give an introduction to the AdS/CFT correspondence and some of its generalizations. I will then discuss some recent results concerning the physics of heavy quarks in a hot plasma.

Prof. Dr. Johanna Stachel (PI Heidelberg) & Dr. Alexander Rothkopf (ITP Heidelberg)
Quarkonia as probes of deconfinement at the LHC
[Wednesday, July 6, 16:15 h, Physikalisches Institut, INF 226, SR 01.106]
[slides of J. Stachel], [slides of A. Rothkopf]Experimental data on quarkonia at the LHC, including the very recently released first results from run 2, are summarized. The focus will be on PbPb collisions, but the most relevant data from pp and pPb collisions will be included. Data will be compared to the statistical hadronization model and to some transport model calculations. The theory part presents the latest results on kinetically thermalized heavy quarkantiquark bound states using lattice QCD input. Based on the lattice inmedium heavyquark potential, we compute and discuss finite temperature spectral functions for Charmonium and Bottomonium. These form the basis for estimating e.g. the J/Psi / Psi’ ratio at freezeout or the modification of feeddown fractions from the Pwave to the Swave states.

Prof. Dr. Peter BraunMunzinger (GSI Darmstadt & PI Heidelberg) & Dr. Stefan Floerchinger (ITP Heidelberg)
Probability distributions and moments of hadron production in relativistic nuclear collisions: theoretical perspectives and experimental challenges
[Wednesday, June 22, 16:15 h, Physikalisches Institut, INF 226, SR 01.106]
[sildes of P. BraunMunzinger], [slides of S. Floerchinger]Introduction and perspective
Hadron production, Lattice QCD and the QCD phase structure
Susceptibilities and 1st moments
Higher moments – the experimental challenges
Experimental outlook
Theory of fluctuations and correlations in QCD matter
Freezeout with correlations
Theoretical challenges 
Prof. Dr. Raju Venugopalan (BNL Brookhaven & ITP Heidelberg)
KibbleZurek dynamics and universal offequilibrium scaling of critical cumulants in the QCD phase diagram
[Wednesday, June 8, 16:15 h, Physikalisches Institut, INF 226, SR 01.106]
[slides]We exploit the universality between the QCD critical point and the three dimensional Ising model to derive closed form expressions for nonequilibrium critical cumulants on the crossover side of the critical point. Novel expressions are obtained for the nonGaussian Skewness and Kurtosis cumulants; our results reveal that they can differ both in magnitude and sign from equilibrium expectations. We show further that key elements of the KibbleZurek framework of nonequilibrium phase transitions can be employed to describe the dynamics of these critical cumulants. As a consequence, observables sensitive to critical dynamics in heavyion collisions are expressible as universal scaling functions and thereby provide powerful model independent guidance in searches for the QCD critical point.

Prof. Dr. Klaus Reygers (PI Heidelberg) & Dr. Naoto Tanji (ITP Heidelberg)
Preequilibrium photon production and the directphoton puzzle
[Wednesday, May 11, 16:15 h, Physikalisches Institut, INF 226, SR 01.106]
[sildes of K. Reygers], [slides of N. Tanji]The observed yield and azimuthal anisotropy of direct photons in heavyion collisions are not well described by hydrodynamic models which nicely fit hadronic observables. This socalled directphoton puzzle challenges the standard model of the spacetime evolution of these collisions. We discuss possible ways to solve this puzzle. In particular, we focus on directphoton Hanbury BrownTwiss correlations as a tool to investigate whether direct photons mostly come from the early or late stage of the collision. On the theoretical side, a better understanding of photon production in the preequilibrium stage of the collisions might help solve the puzzle. Aiming at a firstprinciplebased study of the preequilibrium photon production, the quark production in inhomogeneous classical gauge fields has been calculated by using realtime lattice simulation technique. It will be shown that photons emitted from the produced quarks by a classical process exhibit a thermallike exponential spectrum though the system is far away from equilibrium.

Prof. Dr. Charles Gale (McGill U., Montreal)
QCD under extreme conditions: Hot, shiny fluids and sticky business
[Wednesday, April 27, 17:00 h, Kirchhoff Institute for Physics, INF 227, HS 2]
[slides]The phase diagram of Quantum Chromodynamics (QCD, the theory of the strong interaction) is only poorly known. There is currently a vibrant experimental and theoretical program that concentrate on the study and the characterization of the quarkgluon plasma, a fundamental state of matter that existed a few microseconds after the Big Bang. I will describe the theoretical aspects of this endeavour, and highlight some of the surprises uncovered along the way. In particular, I will spend some time reviewing what can be learned from the study of electromagnetic radiation from those highenergy collisions.