English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

The Sivers function describes the correlation between the transverse spin ofa nucleon and the transverse motion of its partons. It was extracted frommeasurements of the azimuthal asymmetry of hadrons produced in semi-inclusivedeep inelastic scattering of leptons off transversely polarised nucleontargets, and it turned out to be non-zero for quarks. In this letter theevaluation of the Sivers asymmetry for gluons in the same process is presented.The analysis method is based on a Monte Carlo simulation that includes threehard processes: photon-gluon fusion, QCD Compton scattering and leading-ordervirtual-photon absorption process. The Sivers asymmetries of the threeprocesses are simultaneously extracted using the LEPTO event generator and aneural network approach. The method is applied to samples of events containingat least two hadrons with large transverse momentum from the COMPASS data takenwith a 160 GeV/$c$ muon beam scattered off transversely polarised deuterons andprotons. With a significance of more than two standard deviations a negativevalue is obtained for the gluon Sivers asymmetry. The result of a similaranalysis for a Collins-like asymmetry for gluons is consistent with zero.

First measurement of the Sivers asymmetry for gluons from SIDIS data