Measurement of the transverse Single Spin Asymmetry of Forward Eta Mesons in $p^{\uparrow}+p$ Collisions in PHENIX

TL;DR

This paper reports on the measurement of the transverse single spin asymmetry of eta mesons produced in polarized proton-proton collisions at RHIC, aiming to understand nucleon structure and test theoretical models of spin asymmetries.

Contribution

It presents the first measurement of eta meson asymmetries at forward rapidities in polarized proton collisions, providing new data to constrain models of nucleon spin structure.

Findings

Observed non-zero asymmetries in eta meson production.

Provides data to test mechanisms explaining spin asymmetries.

Enhances understanding of nucleon internal spin dynamics.

Abstract

Polarized $p+p$ collisions provide insight into the structure of the nucleon. $A_N$ of eta mesons at forward rapidities are of particular interest, as asymmetries of other mesons observed both by PHENIX and other experiments show significant deviation from zero in the forward region. Several mechanisms have been proposed that attempt to explain these non-zero asymmetries, and a comparison of different probes may further constrain these models. Therefore, measurements of $A_N$ with inclusive eta mesons at forward rapidities are an important tool toward understanding the underlying mechanism. Using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), we study $p^{\uparrow}+p$ collisions. In 2008, the PHENIX experiment collected 5.2 pb$^{-1}$ integrated luminosity in $p^\uparrow+p$ collisions at $\sqrt{s}$ = 200 GeV. The asymmetry analysis of eta mesons at forward rapidity will be discussed.