# SPIN 2018

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

## Double helicity asymmetries for $\pi^{\pm}$ production in $p+p$ collisions at $\sqrt{s}$=510 GeV at PHENIX Mid-rapidity

12 Sep 2018, 17:00
20m

### A10

Parallel Sessions Nucleon Helicity Structure

### Speaker

Mr Taebong Moon (Yonsei University/RIKEN)

### Description

One of the main goals of the RHIC spin program is the determination of the gluon helicity contribution to the proton spin. This can be accessed by measuring double helicity asymmetries ($A_{LL}$) of pion production at mid-rapidity in longitudinally polarized proton collisions. The ordering of the asymmetries with the charge of the final state pions can in addition directly infer the sign of the gluon spin contribution. Charged pions are reconstructed in the central PHENIX tracking system. The asymmetries are evaluated between the collisions of bunches with the same and opposite helicity after correcting for differences in luminosity and for beam polarizations. To extend our understanding of the gluon polarization to a lower gluon momentum fraction ($x$), high statistics data was collected at a higher $\sqrt{s}$=510 GeV in 2012-2013. We present the physics motivation, the analysis procedure, current status of the $\pi^{\pm}$ $A_{LL}$ measurements and comparisons to $\pi^{0}$ as well as $\pi^{\pm}$ at $\sqrt{s}$=200 GeV.

### Primary author

Mr Taebong Moon (Yonsei University/RIKEN)

 Slides