Conformal anomaly as a source of soft photons in heavy ion collisions

TL;DR

This paper proposes a new photon production mechanism in heavy ion collisions based on the conformal anomaly of QCDxQED, which explains observed photon yields and anisotropies, matching experimental data.

Contribution

It introduces a novel photon production mechanism from conformal anomaly effects in QCDxQED within heavy ion collisions, aligning theoretical predictions with experimental observations.

Findings

Photon yield from the anomaly mechanism is comparable to conventional sources.

The mechanism significantly enhances photon azimuthal anisotropy (v2).

Results are consistent with PHENIX experimental data.

Abstract

We introduce a novel photon production mechanism stemming from the conformal anomaly of QCDxQED and the existence of strong (electro)magnetic fields in heavy ion collisions. Using the hydrodynamical description of the bulk modes of QCD plasma, we show that this mechanism leads to the photon production yield that is comparable to the yield from conventional sources. This mechanism also provides a significant positive contribution to the azimuthal anisotropy of photons, $v_2$, as well as to the radial "flow". We compare our results to the data from the PHENIX Collaboration.