Spin Polarized Photons and Di-leptons from Axially Charged Plasma

TL;DR

This paper proposes P- and CP-odd observables in photon and di-lepton emissions from an axially charged QCD plasma, aiming to detect axial charge fluctuations and triangle anomalies in heavy-ion collision experiments.

Contribution

It introduces novel P- and CP-odd observables related to spin alignments of emitted particles, connecting them to the imaginary part of chiral magnetic conductivity and the triangle anomaly.

Findings

Observable calculations in strongly coupled regime using AdS/CFT.

Relation of observables to the imaginary part of chiral magnetic conductivity.

Potential experimental signatures of axial charge fluctuations.

Abstract

Axial charge in a QCD plasma is P- and CP-odd. We propose and study P- and CP-odd observables in photon and di-lepton emissions from an axially charged QCD plasma, which may provide possible experimental evidences of axial charge fluctuation and triangle anomaly in the plasma created in heavy-ion collisions. Our observables measure spin alignments of the emitted photons and di-leptons, and are shown to be related to the imaginary part of chiral magnetic conductivity at finite frequency-momentum, which ultimately arises from the underlying triangle anomaly of the QCD plasma with a finite axial charge density. We present an exemplar computation of these observables in strongly coupled regime using AdS/CFT correspondence.