Göttingen 1997 – wissenschaftliches Programm
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HK: Hadronen und Kerne
HK 8: Struktur von Baryonen und Mesonen I
HK 8.7: Gruppenbericht
Montag, 24. März 1997, 15:45–16:15, HS I
Nucleon parton distributions in the large–Nc limit — •C. Weiss2, D. Diakonov1, V. Petrov1, P. Pobylitsa1,2, and M. Polyakov1,2 — 1Petersburg Nuclear Physics Institute, St. Petersburg — 2Institut f. Theoretische Physik II, Ruhr–Univ. Bochum
At large Nc the nucleon can be viewed as a soliton of the effective chiral lagrangian. This picture allows a consistent calculation of the leading-twist parton distributions at a low normalization point. In this field–theoretic description of the nucleon all important sum rules are satisfied (baryon number, isospin, energy–momentum, Bjorken sum rule). We describe how the polarized and unpolarized distributions (singlet and non-singlet) are derived in the chiral soliton model. We develop a numerical method for computing the quark and antiquark distributions by summation over quark levels (discrete and continuous) in the chiral soliton. The results for unpolarized and polarized distributions compare well with parametrizations of the data at a low normalization point. In particular, we obtain a sizeable fraction of antiquarks. We discuss the concept of the constituent quark in DIS and the gluon distribution from the large–Nc point of view.
[1] D. Diakonov, V. Petrov, P. Pobylitsa, M. Polyakov and C. Weiss, Bochum preprint RUB-TPII-9/96, hep-ph/9606314, Nucl. Phys. B, in press