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The Sivers single-spin asymmetry in photon-jet production

Alessandro Bacchetta·Cedran Bomhof·Umberto D'Alesio·P. J. Mulders·F. Murgia
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Abstract

We study a weighted asymmetry in the azimuthal distribution of photon-jet pairs produced in the process p^\uparrow p --> γjet X with a transversely polarized proton. We focus on the contribution of the Sivers effect only, considering experimental configurations accessible at RHIC-BNL. We show that predictions for the asymmetry, obtained in terms of gluonic-pole cross sections calculable in perturbative QCD, can be tested and clearly discriminated from those based on a generalized parton model, involving standard partonic cross sections. Experimental measurements of the asymmetry will therefore test our present understanding of single-spin asymmetries.

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Alessandro Bacchetta, Cedran Bomhof, Umberto D'Alesio, P. J. Mulders, F. Murgia. 2007-11-22. The Sivers single-spin asymmetry in photon-jet production. https://doi.org/10.1103/physrevlett.99.212002

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