Photon polarization as a probe for quark-gluon plasma dynamics

TL;DR

This paper explores how measuring polarized photons emitted from a quark-gluon plasma can serve as a primary method to detect quark spin polarization, revealing insights into QGP dynamics.

Contribution

It introduces the concept of using circularly polarized photons as a probe for quark polarization in QGP, highlighting the potential enhancement due to momentum space anisotropy.

Findings

Photon polarization can be enhanced by QGP momentum anisotropy.

High-energy photons from oblate distributions show efficient quark polarization transfer.

Photon polarization is not solely caused by QGP anisotropy, but can be influenced by it.

Abstract

Prospects of measuring polarized photons emitted from a quark-gluon plasma (QGP) are discussed. In particular, the detection of a possible quark spin polarization in a QGP using circularly polarized photons emitted from the plasma is studied. Photons leave the QGP without further interaction and thus provide a primary probe for quark polarization within the QGP. We find that photon polarization cannot solely arise due to a possible QGP momentum space anisotropy, but may be enhanced due to it. In particular, for oblate momentum distributions and high photon energies, quark polarization is efficiently transfered to photon polarization. The role of competing sources of polarized photons in heavy-ion collisions is discussed.