# XXVII International Workshop on Deep Inelastic Scattering and Related Subjects

Apr 8 – 12, 2019
Turin
Europe/Rome timezone

## Re-assessment of the nucleon Boer-Mulders function

Apr 10, 2019, 12:10 PM
20m
Rettorato - Aula Principi d'Acaja

### Rettorato - Aula Principi d'Acaja

via Verdi, 8 Turin
Parallel Session Talk WG6: Spin and 3D structure

### Speaker

Prof. Elliot Leader (Imperial College London)

### Description

The presently published Boer-Mulders (BM) function, for a given quark flavour, was extracted from data on semi-inclusive deep inelastic scattering (SIDIS) using the simplifying assumption that it is proportional to the Sivers function for that flavour. We argued that such an assumption is theoretically unacceptable and replaced it with an analogous, theoretically acceptable, relation for the BM valence quark combinations. This modified assumption, as we showed recently [Phys. Rev. D 97 056018, (2018)], is compatible with the COMPASS SIDIS deuteron data on particle-antiparticle difference asymmetries, $A_{UU}^{\cos \phi_h,h-\bar h}$ and $A_{UU}^{\cos 2 \phi_h,h-\bar h}$. Our results suggested that the published information on the BM function might be incorrect. In the present paper, using the standard factorized exponential form for the $k_{\bot, BM}$-dependence of the Boer-Mulders function, but here for the sum of the valence quarks $Q_V(x_B ,Q^2)\equiv u_V(x_B ,Q^2) +d_V(x_B ,Q^2)$, namely, $f_{BM}^{Q_V} \equiv \Delta f^{Q_V}_{BM}(x_B ,Q^2)\, F (k_{\bot, BM})$, we have made the minimal assumption that only the $k_{\bot, BM}$ dependence is the same as in the Sivers case, and we have extracted its collinear part $\Delta f^{Q_V}_{BM}(x_B ,Q^2)$ from the above mentioned data. We show that, indeed, this differs significantly from the same function constructed using the presently published data on the BM function.

### Primary authors

Prof. Elliot Leader (Imperial College London) Dr Ekaterina Christova (Bulgarian Academy of Sciences) Dr Dorota Strozik-Kotlorz (Opole University of Technology)