Shadowing and Absorption Effects on J/psi Production in dA Collisions

Abstract

We study medium modifications of J/psi production in cold nuclear media in deuterium-nucleus collisions. We discuss several parameterizations of the modifications of the parton densities in the nucleus, known as shadowing, an initial-state effect. We also include absorption of the produced J/psi by nucleons, a final-state effect. Both spatially homogeneous and inhomogeneous shadowing and absorption are considered. We use the number of binary nucleon-nucleon collisions as a centrality measure. Results are presented for d+Au collisions at sqrt{S_{NN}} = 200 GeV and for d+Pb collisions at sqrt{S_{NN}} = 6.2 TeV. To contrast the centrality dependence in pA and dA collisions, we also present pPb results at sqrt{S_{NN}} = 8.8 TeV.

Figures (11)

• Figure 1: The shadowing parameterizations are compared at the scale $\mu = 2m_c = 2.4$ GeV. The solid curves are EKS98, the dashed, FGSo, dot-dashed, FGSh, and dotted, FGSl.
• Figure 2: We give the average value of the nucleon momentum fraction, $x_2$, of $J/\psi$ production in $pp$ collisions as a function of rapidity for (a) the CERN SPS with $\sqrt{S} = 19.4$ GeV, (b) RHIC with $\sqrt{S} = 200$ GeV and (c) the LHC with $\sqrt{S} = 6.2$ TeV.
• Figure 3: The WS (dot-dashed) and $\rho$ (solid) inhomogeneous shadowing parameterizations are compared to the inhomogeneous FGS shadowing parameterization (dashed) at the same value of the homogeneous ratio, indicated by the horizontal solid line.
• Figure 4: The $J/\psi$ dAu/$pp$ ratio for absorption alone with $\sigma_{\rm abs} = 3$ mb as a function of impact parameter (left-hand side) and as a function of the number of nucleon-nucleon collisions, $N_{\rm coll}$, (right-hand side) for a constant octet (all $y$), solid, and singlet ($y = -2$), dashed. The homogeneous results are indicated by the dotted lines.
• Figure 5: Left-hand side: The $J/\psi$ dAu/$pp$ ratio with EKS98 at 200 GeV as a function of rapidity for (a) constant octet, (b) growing octet, (c) singlet, all calculated in the CEM and (d) NRQCD. For (a)-(c), the curves are no absorption (solid), $\sigma_{\rm abs} = 1$ (dashed), 3 (dot-dashed) and 5 mb (dotted). For (d), we show no absorption (solid), 1 mb octet/1 mb singlet (dashed), 3 mb octet/3 mb singlet (dot-dashed), and 5 mb octet/3 mb singlet (dotted). Right-hand side: The $J/\psi$ dAu/$pp$ ratio at 200 GeV for a growing octet with $\sigma_{\rm abs} = 3$ mb is compared for four shadowing parameterizations. We show the EKS98 (solid), FGSo (dashed), FGSh (dot-dashed) and FGSl (dotted) results as a function of rapidity.