Angular Correlations in STAR

TL;DR

This paper introduces a method to analyze two-particle angular correlations in heavy ion collisions, linking them to fluctuations, and applies it to STAR data to explore medium interactions and fluctuation sources.

Contribution

It presents a novel general method for determining minimum-bias two-particle correlations and relates these to event-by-event fluctuations in heavy ion collisions.

Findings

Energy dependence of angular correlations observed

Centrality dependence of correlations analyzed

Insights into medium interactions and fluctuation sources gained

Abstract

The related studies of two-particle correlations and event-by-event fluctuations have played important roles in the search for new physics through the experimental study of relativistic heavy ion collisions. We present a general method of determining minimum-bias two-particle correlations and show the relationship between these correlations and event-by-event fluctuations. Data from the STAR experiment at RHIC for Au-Au collisions at $\sqrt{s_{NN}}$ = 62 and 200 GeV will be presented that show the energy and centrality dependences of angular correlations. This analysis provides a unique method for studying the interaction of semi-hard scattered partons with the dense medium produced at RHIC as well as properties of the bulk medium itself, and will shed new light on the sources of non-statistical fluctuations.