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arXiv · 1405.1376

Polarization of Direct Photons from Gluon Anisotropy in Ultrarelativistic Heavy Ion Collisions

Gordon Baym·Tetsuo Hatsuda
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Abstract

We show how anisotropy in momentum of the gluon distribution in ultrarelativistic heavy ion collisions gives rise to polarization of direct photons produced via gluon-quark Compton scattering, as well as by quark-antiquark annihilation into a gluon-photon pair. We estimate the polarization asymmetry from the Compton process within a toy model where the polarized photons are produced from thermal gluons scattered by heavy-quark scattering centers moving with Bjorken boost-invariant flow, and find that it could be as large as 10%. We conclude that polarization measurements of directly produced photons can shed light on gluon pressure anisotropy in the early stages of collisions.

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Gordon Baym, Tetsuo Hatsuda. 2014-05-06. Polarization of Direct Photons from Gluon Anisotropy in Ultrarelativistic Heavy Ion Collisions. https://doi.org/10.1093/ptep/ptv024

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