Understanding LHC jets in the light of RHIC data

Hard probes are a cornerstone in the ongoing program to determine the properties of hot and dense QCD matter as created in ultrarelativistic heavy ion collisions. LHC measurements have so far resulted in a wealth of high P_T data, opening new kinematic windows with high statistics. Yet on first glance, several observations are counter-intuitive and seem to contradict results from the RHIC high P_T program. This calls for a combined analysis of high P_T hadrons and reconstructed jets at RHIC and LHC in a unified framework testing a large number of theoretical models for both medium evolution and shower medium interactions against the systematics of the data. A consistent picture of shower-medium interaction emerges from this analysis which explains where and why results appear counter-intuitive.Comment: 4 pages, 1 figure, talk given at the Quark Matter 2012 International Conference, August 13-18, Washington D.C., US

Theory of Heavy-Ion Collisions

In high energy nucleus-nucleus collisions, a transient state of thermalized, hot and dense matter governed by Quantum Chromodynamics is produced. Properties of this state are reflected in the bulk low transverse momentum (P_T) hadron production which represent the remnant of the collective medium as well as in modifications of so-called probes which are not part of the thermalized medium, i.e. jets generated in high P_T processes or leptons and photons which do not participate in the strong interaction. Theory effords aim at deducing the properties of QCD thermodynamics and collectivity from such observables.Comment: Talk given at the XXIV International Symposium on Lepton Photon Interactions at High Energies, Hamburg, Germany, 17-22 August 200