Transverse Single Spin Asymmetries of charged hadrons at forward and backward rapidity from $p^{\uparrow}+p$, $p^{\uparrow}+\mathrm{Al}$, and $p^{\uparrow}+\mathrm{Au}$ collisions in PHENIX

TL;DR

This paper reports measurements of transverse single spin asymmetries of charged hadrons in polarized proton collisions with protons, aluminum, and gold nuclei, providing insights into the proton's spin structure and nuclear effects at RHIC.

Contribution

It presents the first measurements of TSSAs in $p^{rrow}+A$ collisions, exploring gluon-rich nuclear effects and nuclear modifications of spin asymmetries.

Findings

TSSAs measured at forward and backward rapidity show dependence on nuclear target.

Results indicate potential nuclear effects on spin asymmetries in $p+A$ collisions.

Data provide new constraints for models of proton spin structure and nuclear modifications.

Abstract

Transverse Single Spin Asymmetries (TSSAs) in transversely polarized proton-proton collisions ($p^{\uparrow}+p$) have been a fruitful source for studying the spin structure of the proton. In the 2015 RHIC data taking periods, collisions of polarized protons with nuclei ($p^{\uparrow}+A$) were made for the first time. The measurements of TSSAs in $p^{\uparrow}+p$ and $p^{\uparrow}+A$ collisions can provide a unique opportunity to investigate the origin of TSSA in a gluon-rich target nucleus and provide a tool to study nuclear effects in $p+A$ collisions. This presentation will report PHENIX results of TSSAs for charged hadrons ($h^{\pm}$) at forward and backward rapidity ($1.4<|\eta|<2.4$) over the transverse momentum ranges $1.25<p_{T}<7.0 \mathrm{\ GeV}/c$ and Feynman-$x$ ranges ($-0.2<x_{F}<0.2$) from $p^{\uparrow}+p$, $p^{\uparrow}+\mathrm{Al}$, and $p^{\uparrow}+\mathrm{Au}$ collisions at $\sqrt{s_{\rm NN}}= 200$ GeV.