  A formalism to evaluate the Sivers function, developed for calculations in
constituent quark models, is applied to the Isgur-Karl model. A non-vanishing
Sivers asymmetry, with opposite signs for the u and d flavor, is found; the
Burkardt sum rule is fulfilled up to 2 %. Nuclear effects in the extraction of
neutron single spin asymmetries in semi-inclusive deep inelastic scattering off
3He are also evaluated. In the kinematics of JLab, it is found that the nuclear
effects described by an Impulse Approximation approach are under control.

High Energy Physics - Phenomenology