Pion Boer-Mulders function using a contact interaction

TL;DR

This paper employs a symmetry-preserving contact interaction model to calculate pion transverse momentum dependent parton distribution functions, including the Boer-Mulders function, revealing insights into their mass dependence and gauge link effects.

Contribution

It introduces a novel application of a contact interaction model to compute pion TMDs and explores the effects of gauge links and quark mass dependence on these distributions.

Findings

Quark current mass significantly influences pion TMDs.

Gauge link models impact the positivity bounds of the Boer-Mulders function.

Direct and light-front wave function calculations of TMDs are equivalent.

Abstract

A symmetry preserving treatment of a vector $\otimes$ vector contact interaction (SCI) is used as the basis for calculations of the two pion transverse momentum dependent parton distribution functions (TMDs); namely, that for unpolarised valence degrees-of-freedom and the analogous Boer-Mulders (BM) function. Amongst other things, the analysis enables the following themes to be addressed: the quark current mass dependence of pion TMDs; the impact of the gauge link model on the positivity constraint that bounds the BM function relative to the unpolarised TMD; the equivalence of direct diagrammatic and light-front wave function TMD calculations; and the size of the BM shift. Interpreted astutely, these SCI results enable one to draw insightful pictures of pion TMDs.