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HK: Hadronen und Kerne
HK 55: Structure of Baryons, Mesons VIII, Theory
HK 55.7: Group Report
Wednesday, March 18, 1998, 16:15–16:45, J
Parton distributions at low normalization point in the large–Nc limit — •C. Weiss3, D.I. Diakonov1, V.Yu. Petrov2, P.V. Pobylitsa2, M.V. Polyakov2,3, I. Börnig3, K. Goeke3, D. Urbano3, and T. Watabe3 — 1NORDITA, Copenhagen — 2Petersburg Nuclear Physics Institute, St. Petersburg — 3Institut für Theoretische Physik II, Ruhr–Universität Bochum
We compute the twist–2 quark and antiquark distributions at a low normalization point in the large Nc–limit, where the nucleon can be viewed as a soliton of the effective chiral theory. This is a field–theoretic description of the nucleon which preserves all qualitative properties of parton distributions such as positivity, sum rules etc.. Results for the leading quark and antiquark distributions in the 1/Nc–expansion (isosinglet unpolarized, isovector polarized) and the subleading ones (isovector unpolarized, isosinglet polarized) are compared with parametrizations of the data at a low normalization point. Also studied are the recently discussed off–forward quark distributions, which could be measured in deeply-virtual Compton scattering and hard exclusive meson production.
[1] D.I. Diakonov, V.Yu. Petrov, P.V. Pobylitsa, M.V. Polyakov and C. Weiss, Nucl. Phys. B 480 (1996) 341; Phys. Rev. D 56 (1997) 4069.
[2] V.Yu. Petrov, P.V. Pobylitsa, M.V. Polyakov, I. B"ornig, K. Goeke and C. Weiss, Bochum University preprint RUB-TPII-8/97, hep-ph/9710270.