Two-gluon rapidity correlations of strong colour field in pp, pA and AA collisions

Abstract

Using the CGC formalism, we calculate the two-gluon rapidity correlations of strong colour fields in pp, pA and AA collisions, respectively. If one trigger gluon is fixed at central rapidity, a ridge-like correlation pattern is obtained in symmetry pp and AA collisions, and a huge bump-like correlation pattern is presented in asymmetry pA collisions. It is demonstrated that the ridge-like correlation patterns are caused by the stronger correlation with the gluon of colour source. The transverse momentum and incident energy dependence of the ridge-like correlation pattern is also systematically studied. The ridge is more likely observed at higher incident energy and lower transverse momentum of trigger gluon.

Sub-leading correction of two-gluon rapidity correlations of strong colour field

“…7(a) shows again that the strongest correlation happens when the transverse momenta of two gluon are both the summation of saturation momenta of two incident particles, i.e., p ⊥ = q ⊥ ∼ Q sA + Q sB = 2GeV, as showed by blue line. For each set of transverse momentum, the correlation is enhanced in both short and long rapidity ranges, in contrast to our previous results with fixed coupling constant [35], where the correlation is only enhanced in long rapidity range, and short-range correlations are almost flat, cf., Fig. 4 of [35].…”

“…Fig. 6 (a) shows again that the transverse momentum dependence of the two-gluon rapidity correlations is peaked around the summation of saturation momenta of two incident particles, i.e., p ⊥ ∼ Q sA + Q sB , consistent with our previous results with fixed coupling constant [35]. However, the correlation with running coupling is much stronger than that with fixed coupling constant, cf., the Fig.…”

“…However, the correlation with running coupling is much stronger than that with fixed coupling constant, cf., the Fig. 3 of [35].…”

“…To find the transverse momentum region for the strongest correlations as showed in our previous paper [35], we present firstly in Fig. 6(a) the transverse momentum dependence of two-gluon correlation in given rapidity gaps in pp collisions at √ s = 7 TeV with running coupling.…”

“…In particular, the data of dihadron correlations at RHIC and LHC [19][20][21][22][23][24][25] are qualitatively understood by some of the phenomenological models with the early-time dynamics determined by CGC EFT [26][27][28][29][30][31][32][33][34]. In our previous paper [35], we calculate the two-gluon rapidity correlations of pp, pA and AA collisions in the framework of CGC EFT to leading order of p ⊥ /Q s under fixed coupling constant α s . The results are qualitatively consistent with current data for pPb collisions presented by the ALICE Collaboration [36].…”