We present the first calculation of the transverse spin structure of the pion in lattice QCD. Our simulations are based on two flavors of non-perturbatively improved Wilson fermions, with pion masses as low as 400 MeV in volumes up to (2.1 fm)^3 and lattice spacings below 0.1 fm. We find a characteristic asymmetry in the spatial distribution of transversely polarized quarks. This asymmetry is very similar in magnitude to the analogous asymmetry we previously obtained for quarks in the nucleon. Our results support the hypothesis that all Boer-Mulders functions are alike.
@article{arxiv.0708.2249,
title = {The spin structure of the pion},
author = {D. Brömmel and M. Diehl and M. Göckeler and Ph. Hägler and R. Horsley and Y. Nakamura and D. Pleiter and P. E. L. Rakow and A. Schäfer and G. Schierholz and H. Stüben and J. M. Zanotti},
journal= {arXiv preprint arXiv:0708.2249},
year = {2019}
}
Comments
4 pages, 6 figures; journal version (with original Fig.1 included); updated abstract, text and Figs. 3, 4, 5, 6; added reference; conclusions unchanged