Multipion Bose-Einstein correlations in pp, p-Pb, and Pb-Pb collisions at the LHC

TL;DR

This paper investigates three- and four-pion Bose-Einstein correlations across different collision systems at the LHC, revealing suppression effects in Pb-Pb collisions and exploring potential explanations like coherence or Coulomb effects.

Contribution

It provides the first detailed comparison of multi-pion correlations in pp, p-Pb, and Pb-Pb collisions, introducing methods to search for coherent pion emission.

Findings

Same-charge four-pion correlations in pp and p-Pb are consistent with three-pion expectations.

Significant suppression of multi-pion correlations observed in Pb-Pb collisions.

No clear centrality dependence of suppression within 0-50% centrality range.

Abstract

Three- and four-pion Bose-Einstein correlations are presented in pp, p-Pb, and Pb-Pb collisions at the LHC. We compare our measured four-pion correlations to the expectation derived from two- and three-pion measurements. Such a comparison provides a method to search for coherent pion emission. We also present mixed-charge correlations in order to demonstrate the effectiveness of several analysis procedures such as Coulomb corrections. Same-charge four-pion correlations in pp and p-Pb appear consistent with the expectations from three-pion measurements. However, the presence of non-negligible background correlations in both systems prevent a conclusive statement. In Pb-Pb collisions, we observe a significant suppression of three- and four-pion Bose-Einstein correlations compared to expectations from two-pion measurements. There appears to be no centrality dependence of the suppression within the 0-50% centrality interval. The origin of the suppression is not clear. However, by postulating either coherent pion emission or large multibody Coulomb effects, the suppression may be explained.