Electromagnetic Radiation from Broken Symmetries in Relativistic Nuclear Collisions

This text is meant as an introduction to the theoretical physics of photon emission in hot and dense strongly interacting matter, the principal application being relativistic nuclear collisions. We shall cover some of the results and techniques appropriate for studies at SPS, RHIC, and LHC energies

Various mechanisms of thermal photon production are reviewed and their implications for heavy ion collisions are briefly sketched.

In-medium interactions of a particle in a hot plasma are considered in the framework of thermal field theory. The formalism to calculate gauge invariant rates for photon and dilepton production from the medium is given. In the application to a QED plasma, astrophysical consequences are pointed out. The photon production rate from strongly interacting quarks in the quark--gluon plasma, which might be formed in ultrarelativistic heavy ion collisions, is calculated in the previo...

Long time ago, photon production was proposed as a probe and a thermometer for Quark-Gluon Plasma (QGP). However, only recently has the complete $\alpha_s$ order photon spectrum been obtained. In this paper we give a brief review of the problematic as well as discuss the ${\cal O}(\alpha_s)$ result.

Direct photons have been proposed as a promising signature for the quark-gluon plasma (QGP) formation in relativistic heavy-ion collisions. Recently WA98 presented the first data on direct photons in Pb+Pb-collisions at SPS. At the same time RHIC started with its experimental program. The discovery of the QGP in these experiments relies on a comparison of data with theoretical predictions for QGP signals. In the case of direct photons new results for the production rates of t...

We discuss the production of real or virtual photons in a quark-gluon plasma.

The direct photon radiation from a hot and slightly strong interacting fireball system of a rich baryon quark-gluon plasma, using the Boltzmann distribution function for the incoming particles and Bose-Einstein distribution for gluon and Fermi-Dirac distribution for quark,antiquark and Boltzmann distribution for gluon are discussed subsequently. The first two distribution functions are chosen for the photon production of the first case and the last two functions are considere...

We present an overview of selected aspects of ultrarelativistic nucleus-nucleus collisions, a research program devoted to the study of strongly interacting matter at high energy densities and in particular to the characterization of the quark-gluon plasma (QGP). The basic features of the phase diagram of nuclear matter, as currently understood theoretically, are discussed. The experimental program, carried out over a broad energy domain at various accelerators, is briefly rev...

For tomographic studies of relativistic nuclear collisions and of the quark-gluon plasma, photons (real and virtual) are unique. They are the only probes than can be both soft and penetrating. First we report on advances in modelling the hadron dynamics of heavy-ion collisions using a hybrid approach which consists of IP-Glasma, relativistic fluid dynamics, and hadronic cascade components. We briefly discuss the "photon flow puzzle", and then focus on a recent development in ...

Considering the propagation of off-shell particles in the framework of thermal field theory, we present the general formalism for the calculation of the production rate of soft photons and dileptons from a hot plasma. This approach is illustrated with an electrodynamic plasma. The photon production rate from strongly interacting quarks in the quark-gluon plasma, which might be formed in ultrarelativistic heavy ion collisions, is calculated in the previously unaccessible regim...