BREAKDOWN OF THE HARD THERMAL LOOP EXPANSION FOR QUASI-REAL PHOTONS PRODUCTION

We discuss the bremsstrahlung production of soft real and virtual phot ons in a quark-gluon plasma at thermal equilibrium beyond the Hard The rmal Loop (HTL) resummation. The physics is controlled by the ratio Q( 2)/q(0)(2) of the virtuality to the energy. When Q(2)/q(0)(2) much les s than g(2), where g is the strong coupling constant, the emission rat e is enhanced by a factor 1/g(2) over the HTL results due to light-con e singularities and the bremsstrahlung is induced by scattering of the quark via both transverse and longitudinal soft gluon exchanges.