Towards a model independent extraction of the Boer-Mulders function

TL;DR

This paper presents a model-independent extraction of the Boer-Mulders function from recent experimental data, revealing significant differences from previous assumptions and providing new insights into quark transverse momentum distributions.

Contribution

It introduces a novel method to extract the Boer-Mulders function without relying on the proportionality assumption to the Sivers function, using latest experimental data.

Findings

Significant disagreement with previous Boer-Mulders extractions.

Model-independent determination of the $x_B$-dependence of the Boer-Mulders function.

Insights into the transverse momentum dependence of quark distributions.

Abstract

At present, the Boer-Mulders function for a given quark flavour has been extracted from data on semi-inclusive deep inelastic scattering using the simplifying, but theoretically inconsistent, assumption that it is proportional to the Sivers function for each quark flavour. In this paper, using the latest semi-inclusive deep inelastic COMPASS deuteron data on the $\langle\cos\phi_h\rangle$ and $\langle\cos 2 \phi_h\rangle$ asymmetries we extract the collinear $x_B$-dependence of the Boer-Mulders function for the sum of the valence quarks $Q_V=u_V + d_V$ in an essentially model independent way, and find a significant disagreement with the published results. Our analysis also yields interesting information on the transverse momentum dependence of the unpolarized quark distribution and fragmentation functions.