Estimates for the single-spin asymmetries in $p^{\uparrow}p \to J/\psi X$ process at PHENIX RHIC and SPD NICA

TL;DR

This paper investigates the transverse single-spin asymmetry in proton-proton collisions producing J/psi particles, comparing different theoretical models and using experimental data to constrain gluon Sivers functions, with predictions for future experiments.

Contribution

It provides the first estimates of TSSAs for the SPD NICA experiment and analyzes the dependence of results on hadronization and initial-state models.

Findings

PHENIX data constrains the gluon Sivers function.

One hadronization model is ruled out by data.

Predictions for TSSAs at SPD NICA are presented.

Abstract

We study the transverse single-spin asymmetry (TSSA) in $p^{\uparrow}p \to J/\psi X$ reaction, incorporating both transverse-momentum and spin effects. To predict production cross section of prompt $J/\psi$ we use two different approaches, the non-relativistic QCD (NRQCD) factorization approach and the Improved Color Evaporation Model (ICEM), and show how the predicted results for TSSAs depend on choice of hadronization model. For initial-state factorization we consider two models: the standard Generalized Parton Model (GPM) and the Colour Gauge-Invariant version of it (CGI-GPM). We demonstrate that PHENIX collaboration data on TSSA in the process $p^{\uparrow}p \to J/\psi X$ constrain the gluon Sivers function of the proton and rule-out one of existing parameterizations. Estimates for the TSSAs in $p^{\uparrow}p \to J/\psi X$ process for the conditions of the future SPD NICA experiment are presented for the first time.