Berlin 2005 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 30: Elektromagnetische und Hadronische Proben
HK 30.3: Vortrag
Dienstag, 8. März 2005, 17:15–17:30, TU MA001
Sivers effect in semi-inclusive DIS and the Drell-Yan process — •Simone Menzel1, A.V. Efremov2, K. Goeke1, A. Metz1, and P. Schweitzer1 — 1Institut für Theor. Physik II, Uni Bochum — 2Dubna, JINR, Russland
The Sivers parton distribution describes an azimuthal asymmetry of unpolarized quarks in a transversely polarized target. For quite some time this time-reversal odd function was considered to be zero, and only recently it was proved that it may well exist [1, 2]. In ref.[2] it was predicted that the Sivers function in semi-inclusive DIS and Drell-Yan should have opposite signs. An experimental check of this prediction is still missing. The Sivers asymmetry was measured recently in semi-inclusive DIS by the HERMES collaboration[3]. We use these data to fit the Sivers function and present our results. On this basis we make predictions for the Sivers asymmetry in the Drell-Yan process, which can be measured in the future at the GSI and at COMPASS/CERN via the transverse single spin asymmetries p↑ + p → l + l + X and p↑ + π− → l + l+ X, respectively.
[1] S.J.Brodsky, D.S.Hwang, I.Schmidt, Phys. Lett. B 530, 99 (2002)
[2] J.Collins, Phys. Lett. B 536, 43 (2002)
[3] HERMES, hep-ex/0408013