Constraining quark angular momentum through semi-inclusive measurements

Abstract

The determination of quark angular momentum requires the knowledge of the generalized parton distribution E in the forward limit. We assume a connection between this function and the Sivers transverse-momentum distribution, based on model calculations and theoretical considerations. Using this assumption, we show that it is possible to fit at the same time nucleon magnetic moments and semi-inclusive single-spin asymmetries. This imposes additional constraints on the Sivers function and opens a plausible way to quantifying quark angular momentum.

Comments: 4 pages, 1 figure. Version 2 is similar to publised version, has minor changes in text and bibliography, and the final values of angular momentum are quoted at a different scale compared to Version 1