Abstract
The Sivers effect describes the correlation between the spin of the nucleon and the orbital motion of partons. It can be measured via Semi-Inclusive Deep Inelastic Scattering of lepton on a transversely polarised proton and deuteron targets by determining the azimuthal asymmetry related to the modulation in the Sivers angle ϕSiv. In the paper a method of obtaining the Sivers asymmetry for gluons is presented. It is based on the model of lepton nucleon interactions via three single-photon-exchange processes: photon-gluon fusion (PGF), QCD Compton (QCDC) and leading process (LP). A method of simultaneous extraction of the Sivers asymmetries of the three processes with the use of Monte Carlo (MC) and neural networks (NN) approach is presented. The method has been applied to COMPASS data taken with 160GeV/c muon beam scattered off transversely polarised deuteron and transversely polarised proton target. For each target a data sample of events containing at least two hadrons with large transverse momentum has been selected. Finally the results for gluon Sivers asymmetry were obtained to be: Adg = −0.14 ± 0.15(stat.) ± 0.06(syst.) at 〈xg〉 = 0.13 and Apg = −0.26 ± 0.09(stat.) ± 0.08(syst.) at 〈xg〉 = 0.15.
Highlights
The transverse momentum dependent structure functions of the nucleon have been studied in semi-inclusive DIS on transversely polarised targets for many years
The strongest emphasis has been put on extracting Collins and Sivers asymmetry
To measure the Sivers effect for gluons (PGF Sivers asymmetry) a method of tagging photon-gluon fusion (PGF) process is needed
Summary
This content has been downloaded from IOPscience. Please scroll down to see the full text. Ser. 678 012055 (http://iopscience.iop.org/1742-6596/678/1/012055) View the table of contents for this issue, or go to the journal homepage for more. Download details: IP Address: 188.184.3.52 This content was downloaded on 01/07/2016 at 19:54 Please note that terms and conditions apply
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