Cold nuclear matter effects on J/psi production: intrinsic and extrinsic transverse momentum effects

TL;DR

This paper investigates cold nuclear matter effects on J/psi production in high-energy collisions, considering different partonic processes and kinematics, to better understand nuclear modifications observed at RHIC.

Contribution

It introduces a detailed analysis of intrinsic and extrinsic transverse momentum effects on J/psi production, incorporating specific production kinematics and nuclear shadowing effects.

Findings

Forward rapidity R_AA values are partially explained by the model.

Intrinsic transverse momentum effects influence nuclear modification factors.

Results suggest reduced need for recombination effects at forward rapidity.

Abstract

Cold nuclear matter effects on J/psi production in proton-nucleus and nucleus-nucleus collisions are evaluated taking into account the specific J/psi production kinematics at the partonic level, the shadowing of the initial parton distributions and the absorption in the nuclear matter. We consider two different parton processes for the c-cbar pair production: one with collinear gluons and a recoiling gluon in the final state and the other with initial gluons carrying intrinsic transverse momentum. Our results are compared to RHIC observables. The smaller values of the nuclear modification factor R_AA in the forward rapidity region (with respect to the mid rapidity region) are partially explained, therefore potentially reducing the need for recombination effects.