Direct photon production in relativistic heavy-ion collisions - a theory update

Gale, Charles

doi:10.22323/1.320.0023

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…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]. Current levels of uncertainty in experimental data of real photons at RHIC [62][63][64] and LHC [65] also limits the extent of reliable interpretations of theoretical predictions.…”

Section: Introductionmentioning

confidence: 99%

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

Kasmaei

Strickland

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.

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Section: Introductionmentioning

confidence: 99%

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

Kasmaei

Strickland

2019

Phys. Rev. D

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“…Photons produced in relativistic nuclear collisions have long been recognized as a highly sensitive and unique probe for studying the initial state and its evolution [12,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]. They are also known as the thermometer of the produced matter from the initial days of heavy-ion collisions.…”

Section: Introductionmentioning

confidence: 99%

Probing Relativistic Heavy-Ion Collisions via Photon Anisotropic Flow Ratios. A Brief Review

Chatterjee,

Dasgupta

2024

Physics

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The anisotropic flow of photons produced in relativistic nuclear collisions is known as a promising observable for studying the initial state and the subsequent evolution of the hot and dense medium formed in such collisions. The investigation of photon anisotropic flow coefficients, vn, has attracted high interest over the last decade, involving both theory and experiment. The thermal emission of photons and their anisotropic flow are found to be highly sensitive to the initial state of the fireball, where even slight modifications can lead to significant variations in the final state results. In contrast, the ratio of photon anisotropic flow stands out as a robust observable, exhibiting minimal sensitivity to the initial conditions. Here, we briefly review the studies of the individual elliptic and triangular flow parameters of photons as well as their ratios and how these parameters serve as valuable probes for investigating the intricacies of the initial state and addressing the challenges posed by the direct photon puzzle.

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“…In contrast to other probes like QCD jets [3], photons produced in heavy-ion collisions can escape relatively unscathed as the electromagnetic interaction is much weaker than the strong interaction which governs the QGP evolution -α/α s 1, where α and α s are the fine structure and strong coupling constant respectively. Therefore, the experimental observable chosen to characterize the initial state of relativistic heavy-ion collisions is photon production [4]. To do this, momentum distribution functions of partons are required which appear as solutions of the Boltzmann equation.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic radiation from the pre-equilibrium/pre-hydro stage of the quark-gluon plasma

Churchill,

Yan,

Jeon

et al. 2020

Preprint

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Photons produced in the pre-equilibrium/pre-hydro stage of the quark-gluon plasma produced in relativistic heavy-ion collisions were computed using parton distribution functions obtained from solutions of the Boltzmann equation. The effect of the initial gluon momentum anisotropy ξ and the dependence on the saturation momentum Q s was investigated. We see that small Q s results in a photon yield enhancement, whereas a larger Q s results in a pre-equilibrium photon suppression, owing to the strict constraint of matching to experimental energy density.

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Direct photon production in relativistic heavy-ion collisions - a theory update

Cited by 7 publications

References 15 publications

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

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

Probing Relativistic Heavy-Ion Collisions via Photon Anisotropic Flow Ratios. A Brief Review

Electromagnetic radiation from the pre-equilibrium/pre-hydro stage of the quark-gluon plasma

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