Photons as a viscometer of heavy ion collisions

Abstract

The viscous correction to thermal photon production at leading log order is calculated and integrated over the space-time evolution of a hydrodynamic simulation of heavy-ion collisions. The resulting transverse momentum spectra and elliptic flow can be reliably calculated within a hydrodynamic framework up to transverse momenta of $q_{\perp }$ = 2.5 GeV and $q_{\perp }$ = 1.5 GeV respectively. A non-vanishing viscosity leads to a larger thermalization time when extracted from the experimentally measured inverse slope (T_eff) of photon $q_{\perp }$ spectra. A precise, O(20 MeV), measurement of photon T_eff can place stringent bounds on ${\tau }_0$ and $\eta /s$.

v3: Fixed typos

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Cited by in corpus (42)

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• Hadronic and partonic sources of direct photons in relativistic heavy-ion collisions
• Anisotropic flow of thermal photons as a quark-gluon plasma viscometer
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• Transport coefficients of a hot QCD medium and their relative significance in heavy-ion collisions
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• Thermal photons in QGP and non-ideal effects
• Causal Viscous Hydrodynamics for Relativistic Heavy Ion Collisions
• Cavitation and thermal dilepton production in QGP
• Indications of early thermalization in relativistic heavy-ion collisions
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• Viscous hydrodynamics with bulk viscosity -- uncertainties from relaxation time and initial conditions
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• Anisotropic flow of thermal photons at RHIC and LHC
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• Direct photon production from viscous QGP
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• Transport and hydrodynamic calculations of direct photons at FAIR
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• Hydrodynamical attractor and thermal particle production in heavy-ion collision
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