Pion Boer–Mulders function using a contact interaction

• Published in: The European physical journal. C, Particles and fields Vol. 85; no. 1; pp. 115 - 14
• Main Authors: Cheng, Dan-Dan, Cui, Zhu-Fang, Ding, Minghui, Roberts, Craig D., Schmidt, Sebastian M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 30.01.2025; Springer Nature B.V; SpringerOpen
• Subjects: Astronomy; Astrophysics and Cosmology; Distribution functions; Elementary Particles; Hadrons; Heavy Ions; Impact analysis; Light; Mathematical analysis; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Partons; Physics; Physics and Astronomy; Pions; Quantum Field Theories; Quantum Field Theory; Quarks; Regular Article - Theoretical Physics; String Theory; Transverse momentum; Wave functions
• ISSN: 1434-6052; 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-025-13782-1

A symmetry preserving treatment of a vector  ⊗  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.