Transverse single-spin asymmetry of charged hadrons at forward and backward rapidity in polarized $p$+$p$, $p$+Al, and $p$+Au collisions at $\sqrt{s_{NN}}=200$ GeV}

TL;DR

This paper measures transverse single-spin asymmetries in charged hadron production in polarized proton-proton, proton-aluminum, and proton-gold collisions at 200 GeV, revealing nonzero asymmetries in proton-proton collisions and smaller effects in nuclear collisions, aiding understanding of spin phenomena and nuclear effects.

Contribution

It provides new measurements of $A_N$ in $p^{rrow}$+A collisions at forward and backward rapidity, expanding knowledge of spin asymmetries and nuclear effects in high-energy collisions.

Findings

Nonzero asymmetry observed for positively charged hadrons at forward rapidity in $p^{rrow}$+p collisions.

Smaller asymmetries found in $p^{rrow}$+Al and $p^{rrow}$+Au collisions.

Results offer new insights into the origin of transverse single-spin asymmetries and nuclear effects.

Abstract

Reported here are transverse single-spin asymmetries ($A_{N}$) in the production of charged hadrons as a function of transverse momentum ($p_T$) and Feynman-$x$ ($x_F$) in polarized $p^{\uparrow}$+$p$, $p^{\uparrow}$+Al, and $p^{\uparrow}$+Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. The measurements have been performed at forward and backward rapidity ($1.4<|\eta|<2.4$) over the range of $1.5<p_{T}<7.0~{\rm GeV}/c$ and $0.04<|x_{F}|<0.2$. A nonzero asymmetry is observed for positively charged hadrons at forward rapidity ($x_F>0$) in $p^{\uparrow}$+$p$ collisions, whereas the $p^{\uparrow}$+Al and $p^{\uparrow}$+Au results show smaller asymmetries. This finding provides new opportunities to investigate the origin of transverse single-spin asymmetries and a tool to study nuclear effects in $p$+$A$ collisions.