The ALICE Journal Club will be back on 13 June at 3pm (CEST) with a new interesting lecture. Hendrik van Hees, of the Institute for Theoretical Physics of the Johann-Wolfgang-Goethe-Universität in Frankfurt (Germany), will give a talk on ‘Electromagnetic Probes: Messengers from the hot and dense state’.
In this lecture, van Hees will review the current theoretical understanding of the production of photons and leptons in ultrarelativistic heavy-ion collisions. Since these electromagnetic probes do not participate in the strong interaction, the hot and/or dense medium created in heavy-ion collisions from the lowest to the highest beam energies is transparent for them during the entire evolution of the collision. Hence, the invariant-mass spectrum of dileptons and the transverse-momentum spectra of dileptons and photons provide valuable information about the constituents of hot and/or dense strongly interacting matter, in particular medium modifications of the electromagnetic current-current correlation function, and thus shed light on the question of mass generation of hadrons and the (chiral) phase structure of hot and dense matter. For a realistic theoretical understanding one needs both a detailed model for the strong interactions within a hot and dense medium with partonic as well as hadronic effective degrees of freedom, providing the medium modifications of the current-correlation function, and a description of the dynamics of the medium created in heavy-ion collisions to be able to evaluate the dilepton and photon production in heavy-ion collisions and compare them with the experimental data.