Measurements of multiparticle correlations in +Au Collisions at 200, 62.4, 39, and 19.6 GeV and +Au Collisions at 200 GeV and implications for collective behavior

Aidala, C.*; Hasegawa, Shoichi   ; Imai, Kenichi; Sako, Hiroyuki   ; Sato, Susumu  ; Tanida, Kiyoshi   ; PHENIX Collaboration*; 311 of others*

Recently, multiparticle-correlation measurements of relativistic HeAu, Pb, and even collisions have shown surprising collective signatures. Here we present beam-energy-scan measurements of 2-, 4-, and 6-particle angular correlations in Au collisions at =200, 62.4, 39, and 19.6 GeV. We also present measurements of 2- and 4-particle angular correlations in Au collisions at =200 GeV. We find the 4-particle cumulant to be real-valued for Au collisions at all four energies. We also find that the 4-particle cumulant in Au has the opposite sign as that in 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 Au collisions at 200 GeV, which indicates that nonflow effects are subdominant and provides strong evidence of collectivity.