Semi-inclusive deep inelastic scattering at small transverse momentum

TL;DR

The paper addresses the challenge of describing one-particle inclusive DIS at small transverse momentum by developing a tree-level factorization framework that uses transverse-m momentum dependent PDFs and FFs up to twist-3. It systematically parameterizes quark-quark and quark-gluon-quark correlators, including Wilson-line induced T-odd functions, and derives explicit expressions for a complete set of SIDIS structure functions. It also connects SIDIS results to inclusive DIS and jet production limits, clarifying the role of the Cahn effect and equation-of-motion constraints. The work provides a unified, self-contained foundation for phenomenology of azimuthal and spin asymmetries in SIDIS, with direct relevance to existing experiments and future measurements.

Abstract

We study the cross section for one-particle inclusive deep inelastic scattering off the nucleon for low transverse momentum of the detected hadron. We decompose the cross section in terms of structure functions and calculate them at tree level in terms of transverse-momentum-dependent parton distribution and fragmentation functions. Our results are complete in the one-photon exchange approximation at leading and first subleading twist accuracy, with both beam and target polarization.