Document Type

Article

Publication Date

2026

DOI

10.1016/j.physletb.2026.140373

Publication Title

Physics Letters B

Volume

876

Pages

140373

Abstract

Using the equations of motion of QCD and Lorentz invariance relations, we show a new, more direct way of obtaining a sum rule for the proton’s quark transverse angular momentum in terms of contributions identified as spin and orbital components. The new sum rule can be understood as a twist-three relation, with the parton distribution gT encoding the quark transverse spin. We find that the complementary orbital component can be expressed in terms of a moment in the quark transverse momentum, kT, of the generalized transverse momentum-dependent distribution F₁₂, or alternatively in terms of the twist-three generalized parton distributions H₂T and Ẽ₂T.

Rights

© 2026 The Author(s).

This is an open access article under the Creative Commons Attribution 4.0 International (CC BY 4.0) License.

Data Availability

Article states: "No data was used for the research described in the article."

Original Publication Citation

Alkasassbeh, O., Rajan, A., Engelhardt, M., & Liuti, S. (2026). Transverse orbital angular momentum in the proton. Physics Letters B, 876, Article 140373. https://doi.org/10.1016/j.physletb.2026.140373

ORCID

0000-0002-7066-1723 (Rajan)

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