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

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 $\sqrt{s_{NN}}$ = 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.

8 Pages, 3 Figures, presented at the 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, "QuarkMatter-2008" Jaipur, India, February 4-10, 2008