Identifying the underlying physics of the ridge via 3-particle $\Delta\eta-\Delta\eta$ correlations

TL;DR

This study investigates the 3-particle correlations in heavy-ion collisions to understand the physics behind the ridge phenomenon, revealing uniform distribution over large pseudorapidity gaps and comparing results with theoretical models.

Contribution

First measurement of 3-particle $ riangle ext{eta}$-$ riangle ext{eta}$ correlations in various collision systems at 200 GeV, providing new insights into the ridge's underlying physics.

Findings

Ridge particles are uniformly distributed over the measured $ riangle ext{eta}$-$ riangle ext{eta}$ region.

Results are consistent with certain theoretical models of the ridge.

The analysis enhances understanding of particle correlations in heavy-ion collisions.

Abstract

We present the first results on 3-particle $\Delta\eta$-$\Delta\eta$ correlations in minimum bias $d$+Au, peripheral and central Au+Au collisions at $\sqrt{{\it s}_{NN}}$ = 200 GeV measured by the STAR experiment. The analysis technique is described in detail. The ridge particles, observed at large $\Delta\eta$ in dihadron correlations in central Au+Au collisions, appear to be uniformly distributed over the measured $\Delta\eta$-$\Delta\eta$ region in 3-particle correlation. The results, together with theoretical models, should help further our understanding of the underlying physics of the ridge.