We consider the recent RHIC data on the transverse single spin asymmetry (SSA) A(N), measured in p(uparrow) p -> pi X processes at mid-rapidity by the PHENIX collaboration. We analyze this experimental information within a hard scattering approach based on a generalized QCD factorization scheme, with unintegrated, transverse momentum dependent (TMD), parton distribution and fragmentation functions. In this kinematical region, only the gluon Sivers effect could give a large contribution to AN; its vanishing value is thus used to give approximate upper limits on the gluon Sivers function (GSF). Additional constraints from the Burkardt sum rule for the Sivers distributions are also discussed.
Constraints on gluon Sivers distribution from RHIC
D'ALESIO, UMBERTO;MELIS, STEFANO;
2007-01-01
Abstract
We consider the recent RHIC data on the transverse single spin asymmetry (SSA) A(N), measured in p(uparrow) p -> pi X processes at mid-rapidity by the PHENIX collaboration. We analyze this experimental information within a hard scattering approach based on a generalized QCD factorization scheme, with unintegrated, transverse momentum dependent (TMD), parton distribution and fragmentation functions. In this kinematical region, only the gluon Sivers effect could give a large contribution to AN; its vanishing value is thus used to give approximate upper limits on the gluon Sivers function (GSF). Additional constraints from the Burkardt sum rule for the Sivers distributions are also discussed.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
