γ\gamma-Radiation of thermalized Quark-Gluon-Plasma

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.Comment: 6 pages, 2 ps figures, Contribution to the Proceedings of "Quark Matter 2002", Nantes, France, 18-24 Jul 200

On the photoproduction of jets at HERA

We discuss the inclusive jet production at HERA in the next-to-leading logarithm approximation. Theoretical uncertainties are considered in some details. We show the importance of the jet rapidity distribution to constrain the parton densities in the photon. A comparison is made with the recent H1 data.Comment: 10 + 7 figures included uuencoded tar-compressed ([email protected]) , ENSLAPP-A-484/94, LPTHE Orsay 94-8

Empirical Emission Functions for LPM Suppression of Photon Emission from Quark-Gluon Plasma

The LPM suppression of photon emission rates from the quark gluon plasma have been studied at different physical conditions of the plasma given by temperature and chemical potentials.The integral equation for the transverse vector function (f(p_t)) consisting of multiple scattering effects is solved for the parameter set {p,k,kappa,T}, for bremsstrahlung and AWS processes. The peak positions of these distributions depend only on the dynamical variable x=(T/kappa)|1/p-1/(p+k)|. Integration over these distributions multiplied by x^2 factor also depends on this variable x,leading to a unique global emission function g(x) for all parameters. Empirical fits to this dimensionless emission function, g(x), are obtained. The photon emission rate calculations with LPM suppression effects reduce to one dimensional integrals involving folding over the empirical g(x) function with appropriate distribution functions and the kinematic factors. Using this approach, the suppression factors for both bremsstrahlung and AWS have been estimated for various chemical potentials and compared with the variational method

QCD calculations of thermal photon and dilepton production

In this talk, I review new developments of QCD calculations of photon and dilepton production rates in a Quark-Gluon plasma. All the rates are now known up to $O(\alpha_s)$ both for photons and dileptons, thanks to the resummation of multiple scatterings. For dileptons, a direct numerical calculation on the lattice attempted recently will also be discussed.Comment: 10 pages, 10 postscript figures, Plenary talk given at Quark-Matter 2002, July 18-24, 2002, Nantes, Franc

Photon and lepton pair production in a quark-gluon plasma

We discuss the production of real or virtual photons in a quark-gluon plasma.Comment: 10 pages, 7 postscript figures, based on talks given in July 2000 at QCD 00, Montpellier, France, and at ICHEP2000, Osaka, Japa

Photon Production in Heavy Ion Collisions

The production of photons in heavy ion collisions is dicussed.Comment: Latex, 9 pages, 1 figur

Photon emission in a hot QCD plasma

Various mechanisms of thermal photon production are reviewed and their implications for heavy ion collisions are briefly sketched.Comment: Talk given at Strong and Electroweak Matter 2004, Helsinki, Finland, June 200

Photon and dilepton production in heavy ion collisions at LHC

We review various production mechanisms of photons and small mass dileptons at large transverse momentum in heavy ion collisions at the LHC. Their relevance as a signal for quark-gluon plasma formation is discussed.Comment: 7 page

ALICE potential for direct photon measurements in p-p and Pb-Pb collisions

The production of direct photons, not coming from hadron decays, at large transverse momentum pT > 2 GeV/c in proton-proton collisions at the LHC, is an interesting process to test the predictions of perturbative Quantum Chromodynamics at the highest energies ever and to put constraints on the gluon density in the proton. Furthermore, they provide a baseline reference for quark-gluon-plasma studies in Pb-Pb collisions. We will present the experimental capabilities of the ALICE electromagnetic calorimeter EMCal to reconstruct the direct and isolated photon spectra in p-p and Pb-Pb collisions

DTUJET--93 Sampling inelastic proton--proton and antiproton--proton collisions according to the two--component Dual Parton Model

A new version of a Monte Carlo Program for hadronic multi-particle production is presented. It is based on the two-component Dual Parton Model which includes the dual topological unitarization of soft and hard cross sections. The model treats both soft (low $p_{\perp}$) and hard (minijet, large $p_{\perp}$) processes in a unified and consistent way. The unified description is important at TeV-energies of hadron colliders, where the hard perturbative cross sections of QCD become large and comparable to the total cross sections.Comment: 20 pages , PHYSZZX, SI-93-