Sivers function in constituent quark models

TL;DR

This paper develops a formalism to calculate the Sivers function within constituent quark models, applies it to the Isgur-Karl model, and examines nuclear effects in semi-inclusive deep inelastic scattering, finding a non-zero asymmetry and compliance with sum rules.

Contribution

It introduces a new formalism for evaluating the Sivers function in constituent quark models and applies it to the Isgur-Karl model, providing insights into spin asymmetries and nuclear effects.

Findings

Non-zero Sivers asymmetry with opposite signs for u and d quarks

Fulfillment of the Burkardt sum rule within 2%

Nuclear effects in 3He are manageable in JLab kinematics

Abstract

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.