Identification of flow-background to subtract in jet-like azimuthal correlation

TL;DR

This paper derives an analytical form for the flow-background in jet-like azimuthal correlations, clarifying the appropriate flow parameter to use and verifying it through simulations, with implications for experimental analyses.

Contribution

It introduces a new analytical expression for flow-background in jet correlations, accounting for cluster correlations and flow, verified by Monte Carlo simulations.

Findings

The flow-background should use the two-particle method excluding non-flow correlations.

The derived formula includes cross-terms between cluster correlation and flow.

Verification confirms the analytical form's validity in simulated data.

Abstract

We derive an analytical form for flow-background to jet-like azimuthal correlation in a cluster approach. We argue that the elliptic flow parameter to use in jet-correlation background is that from two-particle method excluding non-flow correlation unrelated to the reaction plane, but including cross-terms between cluster correlation and cluster flow. We verify our result with Monte Carlo simulations. We discuss implications of our finding in the context of jet-like correlations from STAR and PHENIX.