Charged particle to photon ratio in heavy-ion collisions at RHIC: a different point of view

TL;DR

This paper offers an alternative explanation for the observed variation in charged particle to photon ratios in heavy-ion collisions at RHIC, emphasizing the role of direct photons in the ratio change.

Contribution

It proposes a new perspective attributing the ratio variation to direct photon contributions, differing from previous interpretations.

Findings

Charged particle to photon ratio decreases from 1.4 to 1.2 at higher energies.

Direct photon contributions improve the ratio explanation.

Theoretical predictions align with experimental results.

Abstract

We report an alternative explanation of the variation of charged particle to photon ratio in Cu+Cu collisions and Au+Au collisions from 1.4 $\pm$ 0.1 to 1.2 $\pm$ 0.1 at $\sqrt{\it{s}_{\rm NN}}$ = 62.4 GeV and 200 GeV respectively in STAR experiment at RHIC. Based on the theoretical predictions and experimental results we argue that the additional contribution of direct photons at $\sqrt{\it{s}_{\rm NN}}$ = 200 GeV in both Cu+Cu and Au+Au collisions are improving the ratio $\frac{N_{ch}}{N_{\gamma}}$ to 1.2 $\pm$ 0.1 from 1.4 $\pm$ 0.1.