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Volume 281 - The 26th International Nuclear Physics Conference (INPC2016) - Hot and Dense Nuclear Matter – Friday 16
Direct Virtual Photon Production In Au + Au Collisions At 200 Gev At STAR
C. Yang* on behalf of the STAR collaboration
*corresponding author
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Pre-published on: 2017 May 04
Published on: 2017 May 09
Photons are unique probes to study the fundamental properties of the hot and dense medium created in ultra-relativistic heavy-ion collisions. By minimal interactions with the medium, the photons can bring information about the dynamics of the entire time evolution of the medium.
We report the direct photon invariant yields in the transverse momentum ranges $1\!<\!p_{T}\!<\!3$ GeV/$c$ and $5\!<\!p_{T}\!<\!10$ GeV/$c$ at mid-rapidity derived from the low-mass $e^{+}e^{-}$ invariant mass continuum in 0-80% minimum-bias Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. Centrality dependence of direct photon yields is presented. A clear excess of the invariant yield relative to the yield in $p+p$ scaled by nuclear overlap function $T_{AA}$ is observed in the $p_{T}$ range $1\!<\!p_{T}\!<\!3$ GeV/$c$. The production follows $T_{AA}$ scaling at $p_{T}\!>6$ GeV/$c$.
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