Speaker
Description
Electromagnetic probes are penetrating and are thus particularly useful to study the initial state and the earliest phases of hadron and heavy-ion collisions. However, because of the low cross section the measurements suffer from a small signal to background ratio and are therefore extremely challenging.
Prompt photon and Drell-Yan production are sensitive probes of the initial parton distributions and form an important complement to DIS measurements. I will argue that in the near future, such measurements at the LHC provide unique opportunities to obtain clean information on the initial state of hadrons. In particular forward direct photons should provide access to the low-x gluon structure in protons and nuclei.
Both thermal direct photons and low-mass dileptons contain information on the temperature evolution of the strongly interacting system. Measurements have been performed at RHIC and LHC, and the results are still not fully understood theoretically. It is in particular difficult to simultaneously describe the yield of photons and their azimuthal anisotropy. I will discuss the current status of measurements and their interpretation.
