Transverse Single Spin Asymmetry in $p+p^{\uparrow }\to J/\psi +X$

Abstract

We present estimates of transverse single spin asymmetry (TSSA) in $p+p^{\uparrow }\to J/\psi +X$ within the colour evaporation model of charmonium production in a generalized parton model (GPM) framework, using the recently obtained best fit parameters for the gluon Sivers function (GSF) extracted from PHENIX data on TSSA in $p+p^{\uparrow }\to {\pi }^0+X$ at midrapidity. We calculate asymmetry at $\sqrt{s}=200$ GeV, and compare the results with PHENIX data on TSSA in the process $p+p^{\uparrow }\to J/\psi +X$. We also present estimates for asymmetry at $\sqrt{s}=115$ GeV corresponding to the proposed fixed target experiment AFTER@LHC and at $\sqrt{s}=500$ GeV corresponding to the higher RHIC energy. Finally, we investigate the effect of the transverse momentum dependent (TMD) evolution of the densities involved, on the asymmetry.

Comments: 24 pages, 9 figures