Measurement of Transverse Single-Spin Asymmetries in $\pi^0$ and $\eta$ Meson Production in $\sqrt{s}$ = 200 GeV $p^\uparrow+p$ Collisions with sPHENIX

TL;DR

This paper reports on the measurement of transverse single-spin asymmetries in neutral meson production at RHIC, providing new insights into multi-parton correlations and transverse-momentum dependent effects in polarized proton collisions.

Contribution

It presents the first results from sPHENIX on transverse single-spin asymmetries for $C0$ and $Beta$ mesons at 200 GeV, extending the kinematic coverage of previous RHIC measurements.

Findings

Significant asymmetries observed at mid-rapidity.

Results are consistent with prior PHENIX measurements.

Data provide constraints on transverse-momentum dependent parton distributions.

Abstract

The sPHENIX experiment is a next-generation collider detector at the Relativistic Heavy Ion Collider (RHIC) designed for rare jet and heavy-flavor probes of Au + Au, $p$ + Au, and polarized $p+p$ collisions. The experiment includes a large acceptance, granular electromagnetic calorimeter and very high-rate data acquisition plus trigger system. In RHIC Run-24, sPHENIX sampled 107 $\mathrm{pb}^{-1}$ of collision data with transversely polarized protons at $\sqrt{s}=200$ GeV using an efficient high-$p_T$ photon trigger. This dissertation describes the extraction of transverse single-spin asymmetries in inclusive production of $\pi^0$ and $\eta$ mesons decaying into two photons. Such observables are sensitive to multi-parton correlations in the proton, which are related to transverse-momentum dependent (TMD) effects. The new sPHENIX data set allows for significant extension of the kinematic range covered by previous RHIC mid-rapidity measurements. The results are corrected for background contributions and three different sources of systematic uncertainties are considered: the calculation method, the method of background subtraction, and contributions from possible false asymmetries due to instrumental effects. The results are presented and compared to existing measurements from the PHENIX experiment.