Probing gluon spin-momentum correlations in transversely polarized protons through midrapidity isolated direct photons in $p^{\uparrow }+p$ collisions at $\sqrt{s}=200$ GeV

Abstract

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in $p^{\uparrow }+p$ collisions at $\sqrt{s}=200$ GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a fifty-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

arXiv comment312 authors from 68 institutions, 8 pages, 2 figures, 1 table, 2015 data. v2 is version accepted by Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.html

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Cited by in corpus (8)

• Conceptual design of the Spin Physics Detector
• Azimuthal transverse single-spin asymmetries of inclusive jets and identified hadrons within jets from polarized $pp$ collisions at $\sqrt{s}$ = 200 GeV
• Transverse Nucleon Single-Spin Asymmetry for Single-Inclusive Hadron and Jet Production at NLO Accuracy
• The twist-3 gluon contribution to Sivers asymmetry in $J/\psi$ production in semi-inclusive deep inelastic scattering
• Probing nucleon spin structure in deep-inelastic scattering, proton-proton collisions and Drell-Yan processes
• Transverse-single-spin asymmetries of charged pions at midrapidity in transversely polarized $p+p$ collisions at $\sqrt{s}=200$ GeV
• Reformulation of the twist-3 gluon Sivers effect toward the application to the heavy quarkonium production
• Fragmentation contributions to transverse nucleon spin observables in semi-inclusive deep-inelastic scattering at NLO