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arXiv · 1805.08881

Double Helicity Asymmetries of Forward Neutral Pions from $\sqrt{s}=510$ GeV $pp$ Collisions at STAR

Christopher Dilks
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Abstract

Longitudinally polarized $p+p$ scattering experiments provide access to gluon polarization via measurement of the double helicity asymmetry, $A_{LL}$. At the completion of the 2013 RHIC running period, a significant dataset of $π^{0}$s corresponding to an integrated luminosity of 46 $\text{pb}^{-1}$ (2012) and 8 $\text{pb}^{-1}$ (2013) produced from polarized $p+p$ scattering at $\sqrt{s}=510$ GeV with an average beam polarization of approximately $50\%$ was acquired. The $π^{0}$ kinematics were measured via isolation cones by the STAR Forward Meson Spectrometer, an electromagnetic calorimeter covering a forward pseudorapidity range of $2.6 < η<4$. The asymmetric $qg \to qg$ subprocess becomes more dominant in this forward region than in the midrapidity region; furthermore, asymmetry measurements in the forward region are sensitive to low-$x$ gluons. Progress on $A_{LL}$ determined from forward $π^{0}$ events, complementing previous midrapidity measurements, are presented.

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Christopher Dilks. 2018-05-22. Double Helicity Asymmetries of Forward Neutral Pions from $\sqrt{s}=510$ GeV $pp$ Collisions at STAR. https://doi.org/10.1142/s2010194516600247

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