Measurements of multiparticle correlations in $d$$+$Au collisions at 200, 62.4, 39, and 19.6 GeV and $p$$+$Au collisions at 200 GeV and implications for collective behavior

TL;DR

This study measures multiparticle correlations in $d$+Au and $p$+Au collisions across various energies, revealing signs of collective behavior and geometrical origins of correlations, with implications for understanding the quark-gluon plasma.

Contribution

It provides the first beam-energy-scan measurements of multiparticle correlations in $d$+Au collisions and compares them with $p$+Au results, highlighting the collective nature of observed correlations.

Findings

4-particle cumulant is real-valued at all energies in $d$+Au

Opposite sign of 4-particle cumulant in $p$+Au vs. $d$+Au indicates geometrical collectivity

6-particle cumulant agrees with 4-particle in $d$+Au at 200 GeV, suggesting minimal nonflow effects

Abstract

Recently, multiparticle-correlation measurements of relativistic $p/d/^3$He$+$Au, $p$$+$Pb, and even $p$$+$$p$ collisions have shown surprising collective signatures. Here we present beam-energy-scan measurements of 2-, 4-, and 6-particle angular correlations in $d$$+$Au collisions at $\sqrt{s_{_{NN}}}$=200, 62.4, 39, and 19.6 GeV. We also present measurements of 2- and 4-particle angular correlations in $p$$+$Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV. We find the 4-particle cumulant to be real-valued for $d$$+$Au collisions at all four energies. We also find that the 4-particle cumulant in $p$$+$Au has the opposite sign as that in $d$$+$Au, indicating that the correlations are geometrical and therefore collective in origin. Further we find that the 6-particle cumulant agrees with the 4-particle cumulant in $d$$+$Au collisions at 200 GeV, which indicates that nonflow effects are subdominant and provides strong evidence of collectivity.