# SPIN 2018

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

## Direct photon cross section and double helicity asymmetry at mid-rapidity in $\vec{p}$+$\vec{p}$ collisions at $\sqrt{s}$ = 510 GeV

12 Sep 2018, 16:40
20m

### A10

Parallel Sessions Nucleon Helicity Structure

### Speaker

Prof. Kenneth Barish (UC Riverside)

### Description

Double helicity asymmetries $A_{LL}$ in hadron, jet and direct photon production in $\vec{p}$+$\vec{p}$ collisions at the Relativistic Heavy Ion Collider (RHIC) are sensitive to the gluon helicity contribution to the proton's spin. Unlike hadrons and jet, direct photon production provides clean access to the polarized gluon distribution since there is no hadronization. However, the small direct photon production cross section compared to that of $\pi^0$ and jet production has so far limited its utility in extracting the polarized gluon distribution. With recent increases in RHIC luminosity, we expect this limitation to be partially overcome and try to revisit this golden'' measurement of polarized gluons based on RHIC data from 2013. This analysis measures the direct photon cross section and $A_{LL}$ from the data collected employing the PHENIX detector at mid-rapidity ($|\eta| <$ 0.35). This will be the first direct photon cross section and $A_{LL}$ measurement in $\vec{p}$+$\vec{p}$ at $\sqrt{s}$ = 510 GeV with this detector. In this talk I will present the status of direct photon cross section and $A_{LL}$ analysis.

### Primary authors

Prof. Abhay Deshpande (Stony Brook University) Dr Nils Feege (Stony Brook University) Dr Sanghwa Park (PHENIX Collaboration and Stony Brook University) Mr Zhongling Ji (PHENIX Collaboration and Stony Brook University)

 Slides