Production of energetic dileptons with small invariant masses from the quark-gluon plasma

Thoma, Markus H.; Traxler, Christoph

doi:10.1103/physrevd.56.198

Cited by 44 publications

(68 citation statements)

References 18 publications

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“…The first limit will give the behaviour of the thermal Drell-Yan contribution close to the threshold. The second limit allows us to compare with previous calculations [8,9].…”

Section: B Analytic Expressionsmentioning

confidence: 89%

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Energetic dileptons from the quark-gluon plasma

2008

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In this paper we study the production of energetic di-leptons. We calculate the rate for 2 → 2 processes. The log term is obtained analytically and the constant term is calculated numerically. When the photon mass is of the order of the thermal quark mass, the result is insensitive to the photon mass and the soft logarithmic divergence is regulated by the thermal quark mass, exactly as in the case of real photons. We also consider the production of thermal Drell-Yan dileptons (thermal quark and antiquark pairs produced by virtual photons) and calculate the rate systematically in the context of the hard thermal loop effective theory. We obtain analytic and numerical results. We compare our results with those of previous calculations.

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“…The first limit will give the behaviour of the thermal Drell-Yan contribution close to the threshold. The second limit allows us to compare with previous calculations [8,9].…”

Section: B Analytic Expressionsmentioning

confidence: 89%

“…[9]. These authors attempt to produce a result that is valid at next-to-leading order for q 0 ≫ T ≫ {m f , Q}.…”

Section: Fig 6: the Amplitudes Involved In The Lpm Resummation For Vmentioning

confidence: 99%

Energetic dileptons from the quark-gluon plasma

2008

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“…This means the resummed propagator has a finite width in the physical momentum range (−q < q 0 < q), which cures the pinch singularity problem [23]. Only for quantities for which the pole contribution of the spectral function containing a δ-function contributes, such as in the case of the dilepton production rate to order α 2 α s [24], pinch singularities could arise from products of δ-functions. However, this can only happen, if the arguments of the δ-functions are identical, which occurs only for soft external momenta.…”

Section: Non-equilibriummentioning

confidence: 99%

Equilibrium and non-equilibrium hard thermal loop resummation in the real time formalism

1999

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We investigate the hard thermal loop (HTL) resummation technique, which has been derived by Braaten and Pisarski starting from the imaginary time formalism (ITF). We use the real time formalism (RTF) and consider equilibrium as well as non-equilibrium situations. Choosing the Keldysh representation for the propagators, which simplifies significantly the calculation, we derive the HTL photon self energy and the resummed photon propagator. As an example of the application of the HTL resummation method within the RTF we discuss the damping rate of a hard electron. In particular we show that no pinch singularities appear even in non-equilibrium situations.

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“…Processes that contribute to virtual photon emission in QGP at αα s order [17] and the higher order corrections [18] were reported. The processes qq → gγ * , and qg → qγ * contribute to photon polarization tensor at the order of αα s and appear as the one loop processes in HTL method.…”

Section: Emission Of Virtial Photonsmentioning

confidence: 99%

“…, the equation for the longitudinal part could be written as, (18) This implies that theg is larger than g by a factor m 2 D . Therefore, when the solution for this Eq.18 is obtained and integrated over d 2p…”

Section: Emission Of Virtial Photonsmentioning

confidence: 99%

Generalized emission functions for photon emission from quark-gluon plasma

Suryanarayana¹

2007

Phys. Rev. C

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The Landau-Pomeranchuk-Migdal effects on photon emission from the quark gluon plasma have been studied as a function of photon mass, at a fixed temperature of the plasma. The integral equations for the transverse vector function (f (p ⊥ )) and the longitudinal function (g(p ⊥ )) consisting of multiple scattering effects are solved by the self consistent iterations method and also by the variational method for the variable set {p0, q0, Q 2 }, considering the bremsstrahlung and the aws processes. We define four new dynamical scaling variables,, for bremsstrahlung and aws processes and analyse the transverse and longitudinal components as a function of {p0, q0, Q 2 }. We generalize the concept of photon emission function and we define four new emission functions for massive photon emission represented byThese have been constructed using the exact numerical solutions of the integral equations. These four emission functions have been parameterized by suitable simple empirical fits. In terms of these empirical emission functions, the virtual photon emission from quark gluon plasma reduces to one dimensional integrals that involve folding over the empirical g b,aT,L functions with appropriate quark distribution functions and the kinematic factors. Using this empirical emission functions, we calculated the imaginary part of the photon polarization tensor as a function of photon mass and energy. Quark-gluon plasma, Electromagnetic probes, Landau-Pomeranchuk-Migdal effects, bremsstrahlung, annihilation, photon polarization tensor, photon emission function Quark gluon plasma (QGP) state is expected to be formed in the relativistic heavy ion collisions. In order to identify the plasma or a de-confined state, one needs to study the physical processes in quark matter, that can distinctly and conclusively identify this state of matter, such as parton energy loss leading to jet suppression mechanism. In this context, electromagnetic processes such as photons and dilepton emission are also considered as important signals. Photons and dileptons are emitted at various stages during plasma evolution, for an overview one may see [1,2,3] and the references therein. In depth study of photon emission processes in quarkgluon plasma were reported [4,5] including processes also from hot hadron gas [4]. In the formalism of hard thermal loops [6] (HTL) effective theory, the processes of bremsstrahlung [7] and a crossed process of off-shell annihilation called aws [8,9] contribute to photon emission at the two loop level. These two processes contribute at the leading order O(αα s ) owing to the collinear singularity that is regularized by the effective thermal masses. Higher loop multiple scatterings having a ladder topology also contribute at the same order as the one and two loop processes [10,11]. These higher loop rescatterings, each giving finite decoherent correction to the two loop processes, need to be resummed. This resummation effectively implements the Landau-PomarenchkMigdal (LPM) effects [12,13,14] arising due to rescatter- * In...

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Production of energetic dileptons with small invariant masses from the quark-gluon plasma

Cited by 44 publications

References 18 publications

Energetic dileptons from the quark-gluon plasma

Energetic dileptons from the quark-gluon plasma

Equilibrium and non-equilibrium hard thermal loop resummation in the real time formalism

Generalized emission functions for photon emission from quark-gluon plasma

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