arXiv:hep-ph/0606238·v2·High Energy Physics — Phenomenology
Instanton contribution to the Sivers function
I.O. Cherednikov (1,2,3)🇩🇪 · U. D'Alesio (2)🇮🇹 · N.I. Kochelev (3,4)🇷🇺 · F. Murgia (2) ((1) Ruhr-Universitat, Bochum, Germany, (2) University and INFN, Cagliari, Italy, (3) BLTP, Dubna, Russia, (4) Seoul National University, Seoul, Korea)🇮🇹
Abstract
We study the Sivers function for valence u and d quarks in the proton within the instanton model for QCD vacuum, adopting the MIT bag model wave functions for quarks. Within approaches based on perturbative one-gluon final state interactions a non-zero value of the Sivers function is related to the presence of both S and P wave components in quark wave functions. We show that the instanton-induced chromomagnetic, nonperturbative interaction leads to very specific spin-spin correlations between the struck and spectator quarks, resulting in a non-trivial flavour dependence of the Sivers function. Comparison of the obtained Sivers functions with phenomenological parameterizations is discussed.
Comments: 1+12 pages, 4 ps figures; v2: few references and one sentence added in the introduction; final version published in Phys. Lett. B