Review of nonflow estimation methods and uncertainties in relativistic heavy-ion collisions

TL;DR

This paper reviews various methods for estimating nonflow effects in relativistic heavy-ion collision measurements, highlighting their advantages, limitations, and uncertainties to aid future research.

Contribution

It provides a comprehensive, pedagogical review of nonflow estimation techniques, comparing their effectiveness and uncertainties in heavy-ion collision analyses.

Findings

Different nonflow estimation methods have varying success and limitations.

Estimated nonflow contamination levels and uncertainties are discussed.

A unified review aids future research in heavy-ion collision analysis.

Abstract

Collective anisotropic flow, where particles are correlated over the entire event, is a prominent phenomenon in relativistic heavy-ion collisions and is sensitive to the properties of the matter created in those collisions. It is often measured by two- and multi-particle correlations and is therefore contaminated by nonflow, those genuine few-body correlations unrelated to the global event-wise correlations. Many methods have been devised to estimate nonflow contamination with various degrees of successes and difficulties. Here, we review those methods pedagogically, discussing the pros and cons of each method, and give examples of ballpark estimate of nonflow contamination and associated uncertainties in relativistic heavy-ion collisions. We hope such a review of the various nonflow estimation methods in a single place would prove helpful to future researches.