arXiv:hep-ph/0701006·v3·High Energy Physics — Phenomenology
Transversity and Collins functions from SIDIS and e+e- data
M. Anselmino (1)🇮🇹 · M. Boglione (1)🇮🇹 · U. D'Alesio (2)🇮🇹 · A. Kotzinian (3)🇦🇲 · F. Murgia (2)🇮🇹 · A. Prokudin (1)🇮🇹 · C. Turk (1) ((1) University and INFN, Torino, Italy, (2) University and INFN Cagliari, Italy, (3) Yerevan Physics Institute, Armenia and JINR, Dubna, Russia)🇮🇹
Abstract
A global analysis of the experimental data on azimuthal asymmetries in semi-inclusive deep inelastic scattering (SIDIS), from the HERMES and COMPASS Collaborations, and in e+e- --> h1 h2 X processes, from the BELLE Collaboration, is performed. It results in the extraction of the Collins fragmentation function and, for the first time, of the transversity distribution function for u and d quarks. These turn out to have opposite signs and to be sizably smaller than their positivity bounds. Predictions for the azimuthal asymmetry A_{UT}^{sin(phi_h + phi_S)}, as will soon be measured at JLab and COMPASS operating on a transversely polarized proton target, are then presented.
Comments: Revised version to appear in Phys. Rev. D. Few misprints corrected, new figures