Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collisions
We report the first three-particle coincidence measurement in pseudorapidity ($Δη$) between a high transverse momentum ($p_⊥$) trigger particle and two lower $p_⊥$ associated particles within azimuth $|$$Δφ$$|$$<$0.7 in $\sqrt s_NN$ = 200 GeV $d$+Au and Au+Au collisions. Charge ordering properties are exploited to separate the jet-like component and the ridge (long-range $Δη$ correlation). The results indicate that the particles from the ridge are uncorrelated in $Δη$ not only with the trigger particle but also between themselves event-by-event. In addition, the production of the ridge appears to be uncorrelated to the presence of the narrow jet-like component.