# SPIN 2018

9-14 September 2018
University of Ferrara
Europe/Rome timezone
23RD INTERNATIONAL SPIN SYMPOSIUM

## Transverse Single-Spin Asymmetries of Midrapidity Eta Mesons at PHENIX

11 Sep 2018, 17:55
25m
A4 (Polo degli Adelardi - Via Adelardi, 33)

### A4

#### Polo degli Adelardi - Via Adelardi, 33

Parallel Sessions 3D Structure of the Nucleon: TMDs

### Speaker

Nicole Lewis (PHENIX)

### Description

Transverse single-spin asymmetries (TSSAs) of proton-proton collisions have a long history of revealing the richness of QCD. They were originally measured in fixed target experiments and ignored for a couple decades because it was assumed that they came incalculable soft QCD interactions. But they have been found to persist in collisions up to \sqrt{s} = 510 GeV, well into the perturbative regime of QCD, and yet their origin remains poorly understood. TSSA measurements have allowed for the development of both transverse momentum dependent and collinear twist-3 descriptions of nonperturbative spin-momentum correlations in the nucleons as well as in the process of hadronization. As hadrons, eta mesons are sensitive to both initial- and final-state nonperturbative effects for a mix of parton flavors. Their comparison to neutral pions may provide information on potential effects due to strangeness, isospin, or mass. The status of the TSSA of eta mesons at midrapidty for 200 GeV proton-proton collisions from the PHENIX 2015 data set will be shown.

 Slides