Back-to-Back Correlations of Di-hadrons in dAu Collisions at RHIC

Abstract

We perform a complete theoretical analysis of the azimuthal angular correlation of two-hadron productions in the forward $dAu$ collisions at RHIC in the saturation formalism, and obtain a very good agreement with the experimental data. It is demonstrated that the suppression and broadening of the away side peak provide a unique signal for the onset of the saturation mechanism at small-$x$ in a large nucleus. We emphasize that future experiments of di-hadron correlations in $pA$ collisions at both RHIC and LHC, and in $eA$ collisions at the planned electron-ion collider, shall provide us with a thorough study and understanding of the strong interaction dynamics in the saturation regime.

Figures (2)

• Figure 1: The forward di-pion correlations $C(\Delta \phi)$ of Eq. (\ref{['cp']}) at $y_1\sim y_2\sim 3.2$ in peripheral and central $dAu$ collisions compared to the preliminary data from the STAR collaboration Braidot:2010ig. Centrality definition follows Ref. Braidot:2010ig, where the average impact parameters are found around 6.7fm and 2.7fm accordingly. The grey error band comes from using $P_\perp$ or $\tilde{P}_\perp$ in the hard coefficients in Eq. (\ref{['dijet']}).
• Figure 2: The nuclear suppression factor $J_{dA}$ of Eq. (\ref{['jda']}) for the two particle production in $dAu$ collisions as function of $x_{\rm Au}^{\rm frag}$. The experimental data from PHENIX Adare:2011sc and theory calculations are pedestal contributions subtracted.