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Volume 346 - 23rd International Spin Physics Symposium (SPIN2018) - Parallel Session: Nucleon helicity structure (F. Kunne, W. Melnitchouk and B. Page)
Direct photon cross section and double helicity asymmetry at mid-rapidity in $\overrightarrow{p}$+$\overrightarrow{p}$ collisions at $\sqrt{s}$= 510 GeV
K. Barish,* Z. Jia
*corresponding author
Full text: pdf
Pre-published on: 2019 August 19
Published on: 2019 August 23
Double helicity asymmetries A$_{LL}$ in hadron, jet and direct photon production in $\overrightarrow{p}$+$\overrightarrow{p}$ 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 will measure the direct photon cross section and A$_{LL}$ from the data collected employing the PHENIX detector at mid-rapidity (|η| < 0.35). This will be the first direct photon cross section and A$_{LL}$ measurement in$\overrightarrow{p}$+$\overrightarrow{p}$ at $\sqrt{s}$ = 510 GeV with this detector. We report the current status of analysis and the procedures to measure the direct cross section and A$_{LL}$ .
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