Single-spin asymmetry of J/psi production in p plus p, p plus Al, and p plus Au collisions with transversely polarized proton beams at root s(NN)=200 GeV

Abstract

We report the transverse single-spin asymmetries of J/psi production at forward and backward rapidity, 1.2 < vertical bar y vertical bar < 2.2, as a function of J/psi transverse momentum (p(T)) and Feynman-x (x(F)). The data analyzed were recorded by the PHENIX experiment at the Relativistic Heavy Ion Collider in 2015 from p + p, p thorn Al, and p thorn Au collisions with transversely polarized proton beams at root s(NN) p = 200 GeV. At this collision energy, single-spin asymmetries for heavy-flavor particle production of p thorn p collisions provide access to the spin-dependent gluon distribution and higher-twist correlation functions inside the nucleon, such as the gluon Qiu-Sterman and trigluon correlation functions. Proton thorn nucleus collisions offer an excellent opportunity to study nuclear effects on the correlation functions. The data indicate a positive asymmetry at the two-standard-deviation level in the p thorn p data for 2 GeV= c < pT < 10 GeV= c at backward rapidity and negative asymmetries at the two-standard-deviation level in the p thorn Au data for p(T) < 2 GeV= c at both forward and backward rapidity, while in p thorn Al collisions the asymmetries are consistent with zero within the range of experimental uncertainties.