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Azimuthal Asymmetry of Direct Photons in High Energy Nuclear Collisions

Simon Turbide·Charles Gale·Rainer J. Fries
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Abstract

We show that a sizeable azimuthal asymmetry, characterized by a coefficient v_2, is to be expected for direct photons produced in non-central high energy nuclear collisions. This signal is generated by photons radiated by jets interacting with the surrounding hot plasma. The anisotropy is out of phase by an angle $π/2$ with respect to that associated with the elliptic anisotropy of hadrons, leading to negative values of v_2. Such an asymmetry, if observed, could be a signature for the presence of a quark gluon plasma and would establish the importance of jet-plasma interactions as a source of electromagnetic radiation.

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Simon Turbide, Charles Gale, Rainer J. Fries. 2006-01-10. Azimuthal Asymmetry of Direct Photons in High Energy Nuclear Collisions. https://doi.org/10.1103/physrevlett.96.032303

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