It is commonly believed that the Sivers function has uniquely to do with processes involving a transversely polarized nucleon. In this Letter we show that this is not necessarily the case. We demonstrate that exclusive pion production in unpolarized electron-proton scattering in the forward region is a direct probe of the gluon Sivers function due to its connection to the QCD odderon.
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http://dx.doi.org/10.1103/PhysRevLett.124.172501 | DOI Listing |
Phys Rev Lett
September 2024
Warsaw University of Technology, Institute of Radioelectronics, 00-665 Warsaw, Poland.
New results are presented on a high-statistics measurement of Collins and Sivers asymmetries of charged hadrons produced in deep inelastic scattering of muons on a transversely polarized ^{6}LiD target. The data were taken in 2022 with the COMPASS spectrometer using the 160 GeV muon beam at CERN, statistically balancing the existing data on transversely polarized proton targets. The first results from about two-thirds of the new data have total uncertainties smaller by up to a factor of three compared to the previous deuteron measurements.
View Article and Find Full Text PDFPhys Rev Lett
August 2024
Warsaw University of Technology, Institute of Radioelectronics, 00-665 Warsaw, Poland.
The COMPASS Collaboration performed measurements of the Drell-Yan process in 2015 and 2018 using a 190 GeV/c π^{-} beam impinging on a transversely polarized ammonia target. Combining the data of both years, we present final results on the amplitudes of five azimuthal modulations, which correspond to transverse-spin-dependent azimuthal asymmetries (TSAs) in the dimuon production cross section. Three of them probe the nucleon leading-twist Sivers, transversity, and pretzelosity transverse-momentum dependent (TMD) parton distribution functions (PDFs).
View Article and Find Full Text PDFPhys Rev Lett
March 2021
Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany.
We perform the global analysis of polarized semi-inclusive deep inelastic scattering (SIDIS), pion-induced polarized Drell-Yan (DY) process, and W^{±}/Z boson production data and extract the Sivers function for u, d, s and for sea quarks. We use the framework of transverse momentum dependent factorization at next-to-next-to-next-to leading order (N^{3}LO) accuracy. The Qiu-Sterman function is determined in a model independent way from the extracted Sivers function.
View Article and Find Full Text PDFPhys Rev Lett
December 2020
Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA.
Phys Rev Lett
May 2020
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France.
It is commonly believed that the Sivers function has uniquely to do with processes involving a transversely polarized nucleon. In this Letter we show that this is not necessarily the case. We demonstrate that exclusive pion production in unpolarized electron-proton scattering in the forward region is a direct probe of the gluon Sivers function due to its connection to the QCD odderon.
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