Intrinsic parton motion soft mechanisms and the longitudinal spin asymmetry A_LL in high energy pp -> pi X

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dc.creatorAnselmino, M.
dc.creatorBoglione, M.
dc.creatorD'Alesio, U.
dc.creatorLeader, E.
dc.creatorMelis, S.
dc.creatorMurgia, F.
dc.date2007-10-08
dc.date2008-11-10
dc.date.accessioned2026-07-07T12:13:47Z
dc.date.available2026-07-07T12:13:47Z
dc.descriptionThe longitudinal double spin asymmetry A_LL in the reaction pp --> pi X has been measured at RHIC with extremely interesting consequences. If the gluon polarization in a proton were as big as needed to resolve the famous "spin crisis" then A_LL would be large and positive. Latest RHIC results indicate that A_LL is small and disfavour large positive values of the gluon polarization. We examine whether the soft mechanisms (Collins, Sivers, Boer-Mulders), essential for generating transverse single spin asymmetries, have any significant influence on A_LL, and whether they could alter the conclusion that the gluon polarization is necessarily small. It turns out that the contribution from these effects is essentially negligible.
dc.descriptionRevTeX, 9 pages, 3 eps figures. Revised and shortened version; title slightly modified; figs. 3,4 removed; a new figure for the unpol. cross section added; no changes in results and conclusions; matches the published version
dc.identifierhttps://arxiv.org/abs/0710.1569
dc.identifierhttp://arxiv.org/abs/0710.1569
dc.identifierJ.Phys.G36:015007,2009
dc.identifierdoi:10.1088/0954-3899/36/1/015007
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/210970
dc.subjectHigh Energy Physics - Phenomenology
dc.titleIntrinsic parton motion soft mechanisms and the longitudinal spin asymmetry A_LL in high energy pp -> pi X
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