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arXiv · 1404.2846

Pseudo-Critical Enhancement of Thermal Photons in Relativistic Heavy-Ion Collisions

Hendrik van Hees·Min He·Ralf Rapp
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Abstract

We compute the spectra and elliptic flow of thermal photons emitted in ultrarelativistic heavy-ion collisions (URHICs) at RHIC and LHC. The thermal emission rates are taken from complete leading-order rates for the QGP and hadronic many-body calculations including baryons and antibaryons, as well as meson-exchange reactions (including Bremsstrahlung). We first update previous thermal fireball calculations by implementing a lattice-QCD based equation of state and extend them to compare to recent LHC data. We then scrutinize the space-time evolution of Au-Au collisions at RHIC by employing an ideal hydrodynamic model constrained by bulk- and multistrange-hadron spectra and elliptic flow, including a non-vanishing initial flow. We systematically compare the evolutions of temperature, radial flow, azimuthal anisotropy and four-volume, and exhibit the temperature profile of thermal photon radiation. Based on these insights, we put forward a scenario with a "pseudo-critical enhancement" of thermal emission rates, and investigate its impact on RHIC and LHC direct photon data.

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Hendrik van Hees, Min He, Ralf Rapp. 2014-09-11. Pseudo-Critical Enhancement of Thermal Photons in Relativistic Heavy-Ion Collisions. https://doi.org/10.1016/j.nuclphysa.2014.09.009

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