document: Longitudinal beam and target single-spin asymmetries have been at the center of the attention lately, since they have been measured by the HERMES and CLAS experimental Collaborations [1–4] and more measurements are planned. They were originally believed to be signals of the so-called T-odd fragmentation functions [5], in particular, of the Collins function [6–12]. However, both types of asymmetry can receive contributions also from T-odd distribution functions [13–16], a fact that has often been neglected in analyses. An exhaustive treatment of the contributions of T-odd distribution functions has not been carried out completely so far, especially up to subleading order in an expansion in 1/Q, Q2 being the virtuality of the incident photon and the only hard scale of the process, and including quark mass corrections. It is the purpose of the present work to describe the longitudinal beam and target spin asymmetries in a complete way in terms of leading and subleading twist distribution and fragmentation functions. We consider both single-particle inclusive DIS, e+p→e′+h+X, and single-jet inclusive DIS, e+p→e′+jet+X. We assume factorization holds for these processes, even though at present there is no factorization proof for observables containing subleading-twist transverse-momentum dependent functions (only recently proofs for the leading-twist case have been presented in Refs. [17,18]).
doc_bio_tags: O O O O O O O O O O O O O O O O O O O O O O B I I I I O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O B O O O O O O O O O O O B I I I I I I I O O O O O O O O O O B I O B I O O O O O O O O O O O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O
extractive_keyphrases: collins function describe the longitudinal beam and target spin asymmetries factorization fragmentation functions hermes and clas experimental collaborations incident photon quark twist distribution
abstractive_keyphrases: e+p→e′+h+x e+p→e′+jet+x exhaustive treatment of the contributions of t-odd distribution functions factorization proof for observables containing subleading-twist transverse-momentum dependent functions longitudinal beam and target single-spin asymmetries proofs for the leading-twist case quark mass corrections receive contributions also from t-odd distribution functions single-jet inclusive dis single-particle inclusive dis subleading order in an expansion in 1/q subleading-twist transverse-momentum dependent functions t-odd distribution functions t-odd fragmentation functions