Flow analysis with cumulants: direct calculations

TL;DR

This paper introduces an exact method for calculating multi-particle cumulants in flow analysis, improving accuracy and efficiency over existing approximation-based techniques in heavy-ion collision studies.

Contribution

The paper presents a novel exact calculation method for multi-particle cumulants using flow vector moments, eliminating biases of previous approximation-based methods.

Findings

New exact method for cumulant calculation

Reduces computational complexity compared to looping methods

Provides unbiased flow measurements

Abstract

Anisotropic flow measurements in heavy-ion collisions provide important information on the properties of hot and dense matter. These measurements are based on analysis of azimuthal correlations and might be biased by contributions from correlations that are not related to the initial geometry, so called non-flow. To improve anisotropic flow measurements advanced methods based on multi-particle correlations (cumulants) have been developed to suppress non-flow contribution. These multi-particle correlations can be calculated by looping over all possible multiplets, however this quickly becomes prohibitively CPU intensive. Therefore, the most used technique for cumulant calculations is based on generating functions. This method involves approximations, and has its own biases, which complicates the interpretation of the results. In this paper we present a new exact method for direct calculations of multi-particle cumulants using moments of the flow vectors.