Sivers Asymmetry for the proton and the neutron
Abstract
A formalism is presented to evaluate the Sivers function in constituent quark models. A non-relativistic reduction of the scheme is performed and applied to the Isgur-Karl model. The results obtained are consistent with a sizable Sivers effect and the signs for the u and d flavor contributions turn out to be opposite. The Burkardt Sum Rule is fulfilled to a large extent. After the estimate of the QCD evolution of the results from the momentum scale of the model to the experimental one, a reasonable agreement with the available data is obtained. A calculation of nuclear effects in the extraction of neutron single spin asymmetries in semi-inclusive deep inelastic scattering off 3He is also described. In the kinematics of forth-coming experiments at JLab, it is found that the nuclear effects arising within an Impulse Approximation approach are under control.
Cite
@article{arxiv.0807.2189,
title = {Sivers Asymmetry for the proton and the neutron},
author = {S. Scopetta and A. Courtoy and F. Fratini and V. Vento},
journal= {arXiv preprint arXiv:0807.2189},
year = {2008}
}
Comments
8 pages, 3 figures, Invited talk at the "6th International Conference on Hadronic Physics", ICTP, Trieste, Italy, 12-16 May 2008. To appear in AIP Proceedings Series