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

Abstract

In the framework of Color Glass Condensate (CGC) effective field theory (EFT), we calculate two-gluon rapidity correlations in the leading and sub-leading orders of p ⊥ /Q s . In the leading order, both short-and long-range rapidity correlations are enhanced. In contrast, the contribution of sub-leading order is mainly short range quantum correlations. It is much smaller than that of the leading one, but is not negligible. Transverse momentum dependence of rapidity correlation shows that the leading order is sensitive to the saturation momentum of two incident particles, but the sub-leading one is not.

Fine structures of azimuthal correlations of two gluons in the glasma

“…4 therein). The correlation strength at ∆y = 0 is rather high, compared to that of ∆y = 1 and 2, which is due to the contribution of short range correlation at ∆y = 0 from quantum evolution and is affected by the strength of running coupling [33]. The correlation strength at ∆y = 3 is rather high which is long range correlation in rapidity resulting from longitudinal boost invariance in the picture of color flux tubes of glasma [13].…”

“…The gauge fields A a µ (x)[ρ 1 , ρ 2 ] are solutions of the classical Yang-Mills equations in the forward light cone after the nuclear collision for a fixed configuration of sources ρ a 1,2 in each of the nuclei. For Fourier modes k ⊥ of the color charge densities which obey ρ1,2 (k ⊥ )/k 2 ⊥ 1 (which is the case for Q s k ⊥ ), only numerical solutions for A µ (x) are known [25][26][27][28][29][30][31][32][33]. However, for FIG.…”

Rapidity window dependence of ridge correlations in the glasma

“…When rapidity window extends to [−2.4, 2.4], ridges that can extend to |∆y| = 4 are not as flat as those obtained in CMS measurements, either [1]. It shows that glasma graphs have significant short range rapidity correlations [29].…”

“…To avoid repetition, details can be found in Ref. [26] and our previous paper [28,29]. For pp collision at 7 TeV, Q 2 s0 (with Q s0 the initial value of Q s at x 0 ) is chosen to be 0.168 GeV 2 [21].…”

“…It has been demonstrated that, the strong correlation between radiated gluons and source gluons can explain long range rapidity correlations [28,29]. However, ridge correlations in experiments are usually measured within certain rapidity or pseudorapidity windows.…”