The Drell-Yan process with pions and polarized nucleons

Abstract

The Drell-Yan process provides important information on the internal structure of hadrons including transverse momentum dependent parton distribution functions (TMDs). In this work we present calculations for the Drell-Yan process from collisions of pions and polarized protons at leading twist. The non-perturbative input for the TMDs is taken from the light-front constituent quark model, the spectator model, and available parametrizations of TMDs extracted from the experimental data. Our results are compatible with the first experimental information, and will help to interpret the data from ongoing experiments, as well as allow one to quantitatively assess these models in the future when more precise data will become available.

Structure of the nucleon at leading and subleading twist in the covariant parton model

“…In Figs. 3c and 3d we compare the model predictions for xh ⊥(1)q 1T (x) to the LP'15 fit [46] (where the (1)-moment was extracted, though in phenomenological applications [145,146] the (2)-moment of pretzelosity enters naturally). The present data on the azimuthal asymmetry related to pretzelosity are compatible with zero, which is reflected by the uncertainty band of the LP'15 parametrization for u and d flavors [46].…”

“…Subsequently the smallness of the gq T (x) contribution to g q T (x) was confirmed in experiments [137][138][139] and lattice QCD studies [135,136]. These theoretical and experimental results have been a main motivation for exploring the possibility of WW-and WW-type approximations [39,128,145,146] though it cannot be excluded that gq T (x) might be…”

“…For completeness we remark that the assumption that tilde-terms (and mass terms) are small and numerically negligible has been also applied to TMDs [128,[140][141][142][143][144][145][146]. In this case one speaks of Wandzura-Wilczek-type approximations.…”

“…Such approximations can be tested in SIDIS and Drell-Yan experiments [145][146][147]. In the CPM the relations (25) are exact.…”

Weighted $\sin\left(3ϕ_h -ϕ_S\right)$ asymmetry from pretzelosity in SIDIS at electron ion colliders

“…In Ref. [26], based on the model results and the parametrization for pretzelosity, the sin(2φ + φ S ) azimuthal asymmetry, which is due to the convolution of pretzelosity and pion Boer-Mulders function, was estimated and compared with the COMPASS data.…”