München 2006 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 28: Elektromagnetische und Hadronische Sonden
HK 28.2: Vortrag
Mittwoch, 22. März 2006, 14:15–14:30, F
Phenomenology of the Sivers function — •Simone Menzel1, J.C. Collins2, A.V. Efremov3, K. Goeke1, M. Grosse-Perdekamp4, B. Meredith4, A. Metz1, and P. Schweitzer1 — 1University Bochum, Germany — 2Penn State University, USA. — 3Joint Institute for Nuclear Research, Russia — 4BNL, USA
Recently, the Sivers asymmetry (SA) has been measured in semi-inclusive DIS by the HERMES and the COMPASS Collaborations. These data allow one for the first time to reliably extract the Sivers parton density f1T⊥ (x,k⊥) [1], which describes the distribution of unpolarized partons in a transversely polarized target. Assuming a Gaussian distribution for the transverse momentum dependence of the Sivers function we have fitted the HERMES data [2,3]. On the basis of our fit we made predictions for the SA in the Drell-Yan process (DY) for different experiments (COMPASS, PAX, RHIC) [2,3] and explain their advantages. It turns out that the SA in DY is measurable. It seems possible to check the predicted sign-reversal of the Sivers function when comparing DIS and DY [4] and so to test our understanding of single spin asymmetries in terms of QCD.
[1] D.W.Sivers, Phys.Rev.D, 41:83, 1990
[2] J.C.Collins et al., hep-ph/0511272
[3] J.C.Collins et al., hep-ph/0509076
[4] J.C.Collins, Phys.Lett.B, 536:43, 2002