Bochum 1998 – scientific programme
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HK: Hadronen und Kerne
HK 67: Structure of Baryons, Mesons IX, Theory
HK 67.1: Group Report
Thursday, March 19, 1998, 14:00–14:30, H
Nucleon Structure Functions in a Chiral Soliton Model — •H. Weigel1, L. Gamberg2, and H. Reinhardt1 — 1Institut f"ur Theoretische Physik, Universit"at T"ubingen, D-72076 T"ubingen — 2Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks, Norman, OK 73019, USA
We study nucleon structure functions within the bosonized version of
the Nambu–Jona–Lasinio (NJL) model. In this model the nucleon is
described as a chiral soliton [1]. We start by presenting the
calculation of the unpolarized structure functions for the νp
and νp scattering in the valence quark approximation.
For moderate constituent quark masses (∼ 400MeV) this
approximation is well justified because the contribution of this
distinct level dominates the nucleon properties. By including
cranking corrections to the chiral soliton this approximation is
formulated to be consistent with the Adler sum rule. We continue by
discussing the results for the Gottfried sum rule for electron nucleon
scattering [2]. The comparison with a low–scale parametrization
shows that the model reproduces the gross features of the
empirical structure functions. In addition the issues of projection [3]
and q2–evolution are addressed thereby determining the intrinsic
scale µ2 associated with the NJL chiral soliton. We also compute
the leading twist contributions of the polarized structure functions
g1 and g2 in this model [4]. We compare the model predictions for
these structure functions with data from SLAC by evolving them from the
scale µ2 to the scale where the data are taken. We furthermore
analyse the chiral–odd structure functions h1 and hL in an
analogous manner. In the light of various sum rules for the structure
functions we finally comment on the problem of consistently
regularizing the contribution due to the quark vacuum which is
polarized by the background field of the chiral soliton.
[1] R. Alkofer, H. Reinhardt, H. Weigel, Phys. Rep. 265 (1996) 139.
[2] H. Weigel, L. Gamberg, H. Reinhardt, Mod. Phys. Lett. A11, 3021 (1996); Phys. Lett. B399 (1997) 287.
[3] L. Gamberg, H. Reinhardt, H. Weigel, hep–ph/9707352.
[4] H. Weigel, L. Gamberg, H. Reinhardt, Phys. Rev. D55 (1997) 6910.
Supported in part by the Deutsche
Forschungsgemeinschaft (DFG) under contract
Re 856/2–3.