Single transverse spin asymmetry of prompt photon production

Abstract

We study the single transverse spin asymmetry of prompt photon production in high energy proton-proton scattering. We include the contributions from both the direct and fragmentation photons. While the asymmetry for direct photon production receives only the Sivers type of contribution, the asymmetry for fragmentation photons receives both the Sivers and Collins types of contributions. We make a model calculation for quark-to-photon Collins function, which is then used to estimate the Collins asymmetry for fragmentation photons. We find that the Collins asymmetry for fragmentation photons is very small, thus the single transverse spin asymmetry of prompt photon production is mainly coming from the Sivers asymmetry in direct and fragmentation photons. We make predictions for the prompt photon spin asymmetry at RHIC energy, and emphasize the importance of such a measurement.

11 pages 7 figures, additional discussion, 1 figure added, matches published version in Phys. Lett. B

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Cited by in corpus (20)

• Parton Fragmentation Functions
• QCD Evolution of the Sivers Asymmetry
• Fragmentation contribution to the transverse single-spin asymmetry in proton-proton collisions
• The RHIC SPIN Program: Achievements and Future Opportunities
• Indication on the process-dependence of the Sivers effect
• A Fixed-Target Programme at the LHC: Physics Case and Projected Performances for Heavy-Ion, Hadron, Spin and Astroparticle Studies
• Transverse spin effects in hard semi-inclusive collisions
• Transverse momentum-weighted Sivers asymmetry in semi-inclusive deep inelastic scattering at next-to-leading order
• Transverse single spin asymmetry in hadronic ${\eta }_{c,b}$ production
• Multiple scattering effects on inclusive particle production in the large-x regime
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• A Proposal for the Muon Piston Calorimeter Extension (MPC-EX) to the PHENIX Experiment at RHIC