Photon production from a nonequilibrium quark-gluon plasma

2018

Phys. Rev. D

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We introduce an efficient general method for calculating the self-energies, collective modes, and dispersion relations of quarks and gluons in a momentum-anisotropic high-temperature quark-gluon plasma. The method introduced is applicable to the most general classes of deformed anisotropic momentum distributions and the resulting self-energies are expressed in terms of a series of hypergeometric basis functions which are valid in the entire complex phase-velocity plane. Comparing to direct numerical integration of the self-energies, the proposed method is orders of magnitude faster and provides results with similar or better accuracy. To extend previous studies and demonstrate the application of the proposed method, we present numerical results for the parton self-energies and dispersion relations of partonic collective excitations for the case of an ellipsoidal momentum-space anisotropy. Finally, we also present, for the first time, the gluon unstable mode growth rate for the case of an ellipsoidal momentum-space anisotropy.

Section: Discussionmentioning

confidence: 99%

Parton self-energies for general momentum-space anisotropy

Kasmaei

2018

Phys. Rev. D

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“…In particular, real photons produced in heavy-ion collisions can be emitted from different sources and stages and are affected by various characteristics of the QCD matter . In recent years, phenomenological studies of photon emission using hydrodynamic modeling of heavy-ion collisions have been developing [51][52][53][54][55][56][57][58][59][60][61] towards connecting theoretical ideas to experimental data. However, simultaneous quantitative description of photon yield and flow coefficients has been challenging [6].…”

Section: Introductionmentioning

confidence: 99%

“…Modification of the photon production rate due to momentum anisotropy has also been studied [50] using the parametrization introduced in [73] where momentum anisotropy is described by spheroidal deformation of conventional isotropic distributions. Using the photon rate and an early version of anisotropic hydrodynamics using a spheroidal parametrization, the yield and v 2 of photons from QGP has been studied previously [54]. In this paper, for first time we include in LRF photon rate calculation the momentum anisotropy in transverse direction in the form of ellipsoidal deformation of isotropic distributions.…”

Section: Introductionmentioning

confidence: 99%

Dilepton production and elliptic flow from an anisotropic quark-gluon plasma

Kasmaei

2019

Phys. Rev. D

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The emission of real photons from a momentum-anisotropic quark-gluon plasma (QGP) is affected by both the collective flow of the radiating medium and the modification of local rest frame emission rate due to the anisotropic momentum distribution of partonic degrees of freedom. In this paper, we first calculate the photon production rate from an ellipsoidally momentum-anisotropic QGP including hard contributions from Compton scattering and quark pair annihilation and soft contribution calculated using the hard thermal loop (HTL) approximation. We introduce a parametrization of the nonequilibrium rate in order to facilitate its further application in yield and flow calculations. We convolve the anisotropic photon rate with the space-time evolution of QGP provided by 3+1d anisotropic hydrodynamics (aHydro) to obtain the yield and the elliptic flow coefficient v 2 of photons from QGP generated at Pb-Pb collisions at LHC at 2.76 TeV and Au-Au collisions at RHIC at 200 GeV. We investigate the effects of various parameters on the results. In particular we analyze the sensitivity of results to initial momentum anisotropy.

“…Refs. [170,[179][180][181][182][183][184][185][186], however, in most cases these studies were limited to conformal aHydro with a single anisotropy parameter.…”

Section: Discussionmentioning

confidence: 99%

Relativistic anisotropic hydrodynamics

Alqahtani

Nopoush

Progress in Particle and Nuclear Physics

2018

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118

In this paper we review recent progress in relativistic anisotropic hydrodynamics. We begin with a pedagogical introduction to the topic which takes into account the advances in our understanding of this topic since its inception. We consider both conformal and non-conformal systems and demonstrate how one can implement a realistic equation of state using a quasiparticle approach. We then consider the inclusion of non-spheroidal (non-ellipsoidal) corrections to leadingorder anisotropic hydrodynamics and present the findings of the resulting second-order viscous anisotropic hydrodynamics framework. We compare the results obtained in both the conformal and non-conformal cases with exact solutions to the Boltzmann equation and demonstrate that, in all known cases, anisotropic hydrodynamics best reproduces the exact solutions. Based on this success, we then discuss the phenomenological application of anisotropic hydrodynamics. Along these lines, we review techniques which can be used to convert a momentum-space anisotropic fluid into hadronic degrees of freedom by generalizing the original idea of Cooper-Frye freeze-out to momentum-space anisotropic systems. And, finally, we present phenomenological results of 3+1d quasiparticle anisotropic hydrodynamic simulations and compare them to experimental data produced in 2.76 TeV Pb-Pb collisions at the LHC. Our results indicate that anisotropic hydrodynamics provides a promising framework for describing the dynamics of the momentum-space anisotropic QGP created in heavy-ion collisions.