Towards a first estimate of the gluon Sivers function from A N data in pp collisions at RHIC

U D’Alesio,C Pisano,F Murgia

doi:10.1007/jhep09(2015)119

U D’Alesio, C Pisano + Show 1 more

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https://doi.org/10.1007/jhep09(2015)119

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Abstract

Within a generalized parton model approach, with inclusion of spin and intrinsic transverse momentum effects, we show how the latest, highly precise, midrapidity data on the transverse single spin asymmetry measured in $pp\to\pi^0\, X$ by the PHENIX Collaboration at RHIC [1], can be used to get a first estimate on the still poorly known gluon Sivers distribution. To this end we also adopt the present information on the quark Sivers functions, as extracted from semi-inclusive deeply inelastic scattering data. This analysis updates a previous study by some of us where a first bound on this distribution was obtained [2].

Highlights

Much phenomenological information has been collected on quark TMDs; in particular the Sivers distribution [42, 43] and the Collins fragmentation function [44] have been extracted from SIDIS and e+e− data by different groups [25, 45,46,47,48,49,50,51,52,53]
Within a generalized parton model approach, with inclusion of spin and intrinsic transverse momentum effects, we show how the latest, highly precise, midrapidity data on the transverse single spin asymmetry measured in pp → π0 X by the PHENIX Collaboration at RHIC [1], can be used to get a first estimate on the still poorly known gluon Sivers distribution
√ In figure 1 we present our results for AN at s = 200 GeV and midrapidity, compared with PHENIX data [1] and adopting the SIDIS2 [50] extraction of the quark Sivers functions

Summary

Introduction

Much phenomenological information has been collected on quark TMDs; in particular the Sivers distribution [42, 43] and the Collins fragmentation function [44] have been extracted from SIDIS and e+e− data by different groups [25, 45,46,47,48,49,50,51,52,53]. Best estimate of the SSA AN , red solid line, compared with PHENIX data [1] at s = 200 GeV and at midrapidity, as a function of PT and adopting the SIDIS2 extraction for the quark Sivers functions [50].

Results

Conclusion