A new extraction of the Boer-Mulders function

Abstract

At present, the Boer-Mulders function for a given quark flavour has been extracted from data on semi-inclusive deep inelastic scattering using the simplifying, but theoretically inconsistent, assumption that it is proportional to the Sivers function for each quark flavour. In this paper, using the latest semi-inclusive deep inelastic COMPASS deuteron data on the cos φ h and cos 2φ h asymmetries we extract the collinear x B -dependence of the Boer-Mulders function for the sum of the valence quarks QV = uV + dV in an essentially model independent way, and find a significant disagreement with the published results. Our analysis also yields interesting information on the transverse momentum dependence of the unpolarized quark distribution and fragmentation functions.

Transverse spin effects in hard semi-inclusive collisions

“…Similar relations to SIDIS observables can be found for the other TMDs [15,16]; in particular the Boer-Mulders function, which contributes to F cos 2φ h U U , has been studied [135,136] and some data are available [137,138,139,140,141]. We do not discuss here these TMDs; in Sections 3.5, 4.1, 4.2 and 4.3 we look in more details at our actual knowledge of the Collins, the unpolarised, the Sivers and the transversity TMDs, emphasising what we learn from them about the nucleon structure.…”