Abstract. The emission of hard real photons from a quark-gluon plasma at high temperatures is studied. At lowest order the QCD processes for quark-antiquark annihilation (qq--*79) and for Compton scattering (qg~Tq) lead to logarithmically divergent thermal production rates for massless quarks. By applying recently developed resummation methods of finite temperature perturbation theory we show that effects due to Landau damping on the exchanged quark provide finite rates. Comparisons with previous estimates and phenomenological implications are discussed.
We consider thermal n-point Green functions in the framework of quantum field theory at finite temperature. We show how analytic continuations from imaginary to real energies relate these functions originally defined in the imaginary-time formalism to retarded and advanced real-time ones. The described method is valid to all orders of perturbation theory. It has the further advantage that it is independent of approximations often applied in actual finite-order calculations. 02.30.Fn, 03.70.+k, 11.10.Ef
A study is made of a path-integral representation of the generating functional for the real-time thermal Green's functions in quantum field theories. The bare thermal propagator is shown to obey the Kubo-Martin-Schwinger condition. It is verified that the statistical factors in thermal propagators with momentum p should be regarded as functions of l p o rather than of (p2+ m2)'". Also rederived is the bare thermal gauge field propagator in a covariant gauge.
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