# Are There Mach Cones in Heavy Ion Collisions? Three-Particle Correlations from STAR

## TL;DR

This paper investigates three-particle azimuthal correlations in heavy ion collisions to identify potential conical emission patterns, distinguishing them from other phenomena like QCD-Cerenkov radiation through detailed background subtraction and flow analysis.

## Contribution

It provides the first detailed analysis of three-particle correlations in heavy ion collisions to search for Mach cone signals and differentiates conical flow from other effects.

## Key findings

- Observation of three-particle correlations suggestive of conical emission in Au+Au collisions
- Dependence of correlation angles on particle transverse momentum helps distinguish flow from Cerenkov radiation
- Systematic analysis of background subtraction and flow harmonics enhances result reliability

## Abstract

We present results from STAR on 3-particle azimuthal correlations for a $3<p_T<4$ GeV/c trigger particle with two softer $1<p_T<2$ GeV/c particles. Results are shown for pp, d+Au and high statistics Au+Au collisions at $\sqrt{s_{NN}}=200 GeV$. We observe a 3-particle correlation in central Au+Au collisions which may indicate the presence of conical emission. In addition, the dependence of the observed signal angular position on the $p_T$ of the associated particles can be used to distinguish conical flow from simple QCD-\v{C}erenkov radiation. An important aspect of the analysis is the subtraction of combinatorial backgrounds. Systematic uncertainties due to this subtraction and the flow harmonics $v_2$ and $v_4$ are investigated in detail.