Production rate of hard thermal photons and screening of quark mass singularity

Baier, Rudolf; Nakkagawa, Hisao; Niégawa, A.; Redlich, K.

doi:10.1007/bf01625902

Cited by 239 publications

(331 citation statements)

References 27 publications

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“…In the particular case of the photon production rate, it is the Landau damping of a soft fermion which provides infrared finiteness [197,198] (in the bare perturbation theory, there is a logarithmic divergence associated with the exchange of a massless quark). Another example where the resummation enters in a decisive way is the calculation of the production rate of soft dileptons in a hot quarkgluon plasma [202].…”

Section: Some Applications Of Htl-resummed Perturbation Theorymentioning

confidence: 99%

The quark–gluon plasma: collective dynamics and hard thermal loops

Blaizot¹,

Iancu²

2002

Physics Reports

511

714

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We present a unified description of the high temperature phase of QCD, the so-called quark-gluon plasma, in a regime where the effective gauge coupling g is sufficiently small to allow for weak coupling calculations. The main focuss is the construction of the effective theory for the collective excitations which develop at a typical scale gT , which is well separated from the typical energy of single particle excitations which is the temperature T . We show that the short wavelength thermal fluctuations, i.e., the plasma particles, provide a source for long wavelength oscillations of average fields which carry the quantum numbers of the plasma constituents, the quarks and the gluons. To leading order in g, the plasma particles obey simple gauge-covariant kinetic equations, whose derivation from the general Dyson-Schwinger equations is outlined. By solving these equations, we effectively integrate out the hard degrees of freedom, and are left with an effective theory for the soft collective excitations. As a by-product, the "hard thermal loops" emerge naturally in a physically transparent framework. We show that the collective excitations can be described in terms of classical fields, and develop for these a Hamiltonian formalism. This can be used to estimate the effect of the soft thermal fluctuations on the correlation functions. The effect of collisions among the hard particles is also studied. In particular we discuss how the collisions affect the lifetimes of quasiparticle excitations in a regime where the mean free path is comparable with the range of the relevant interactions. Collisions play also a decisive role in the construction a Member of CNRS. E-mail: blaizot@spht.saclay.cea.fr b Member of CNRS. E-mail: iancu@spht.saclay.cea.fr c Laboratoire de la Direction des Sciences de la Matière du Commissariatà l'Energie Atomique of the effective theory for ultrasoft excitations, with momenta ∼ g 2 T , a topic which is briefly addressed at the end of this paper.

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Section: Some Applications Of Htl-resummed Perturbation Theorymentioning

confidence: 99%

The quark–gluon plasma: collective dynamics and hard thermal loops

Blaizot¹,

Iancu²

2002

Physics Reports

511

714

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“…(17) and in the following, we write the functions f ∓ in terms of z = ω/k and for clarity do not always state the explicit dependence of f ∓ on k and ξ. Choosing the path depicted in Fig.…”

Section: Nyquist Analysismentioning

confidence: 99%

Fermionic collective modes of an anisotropic quark-gluon plasma

Schenke

Strickland

2006

Phys. Rev. D

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We determine the fermionic collective modes of a quark-gluon plasma which is anisotropic in momentum space. We calculate the fermion self-energy in both the imaginary-and real-time formalisms and find that numerically and analytically (for two special cases) there are no unstable fermionic modes. In addition we demonstrate that in the hard-loop limit the Kubo-MartinSchwinger condition, which relates the off-diagonal components of the real-time fermion self-energy, holds even for the anisotropic, and therefore non-equilibrium, quark-gluon plasma considered here. The results obtained here set the stage for the calculation of the non-equilibrium photon production rate from an anisotropic quark-gluon plasma.

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“…The photon emission rate from a quark-gluon plasma has been perturbatively estimated by various groups [71,72,73] to leading order in the electromagnetic and strong coupling constants. However, there are complications due to leading logs that arise from multiple scattering of co-linear bremsstrahlung (Landau-PomeranchukMigdal (LPM) effect).…”

Section: Transport Propertiesmentioning

confidence: 99%