Studying the Sivers function by model calculations

TL;DR

This paper develops a formalism to calculate the Sivers function using constituent quark models, applying it to the Isgur-Karl model, and compares the results with experimental data after QCD evolution.

Contribution

It introduces a non-relativistic formalism for the Sivers function within constituent quark models and applies it to the Isgur-Karl model, providing insights into flavor contributions and sum rule fulfillment.

Findings

Opposite signs for u and d flavor contributions

Large fulfillment of the Burkardt Sum Rule

Reasonable agreement with experimental data after QCD evolution

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 sign for the $u$ and $d$ flavor contributions that we obtained turns 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.