https://doi.org/10.1140/epjc/s10052-025-13782-1
Regular Article - Theoretical Physics
Pion Boer–Mulders function using a contact interaction
1
School of Physics, Nanjing University, 210093, Nanjing, Jiangsu, China
2
Institute for Nonperturbative Physics, Nanjing University, 210093, Nanjing, Jiangsu, China
3
Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
4
Technische Universiät Dresden, 01062, Dresden, Germany
a
phycui@nju.edu.cn
b
cdroberts@nju.edu.cn
Received:
26
September
2024
Accepted:
30
December
2024
Published online:
30
January
2025
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.
© The Author(s) 2025
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