Informal Pizza Seminar

Hard Probes in Heavy Ion Collisions -
Photons and Jet Quenching

Thorsten Renk

Duke University

Hard probes such as direct photons and the quenching of jets predominantly reflect properties of the early, hot stages of an heavy-ion collision and are potentially capable of probing the QGP directly. However, the measured data are always the result of a convolution of the underlying process (photon emission, jet production/energy loss) with the fireball evolution, and special care has to be taken to disentangle these two. I illustrate the problem how different assumptions about the spacetime evolution of the fireball influence the interpretation of the measurements and argue that arising ambiguities can be (partially) resolved by demanding consistency with other observables at soft scales.