On Electroweak Moments of Baryons and Spin-Flavour Structure of the Nucleon

Abstract

The phenomenological sum-rule-based approach is used to discuss the quark composition dependence of some static and quasi-static electroweak characteristics of nucleons.The role of nonvalence degrees of freedom, the nucleon sea partons and/or peripheral meson currents, is shown to be important to select and make use of the relevant symmetry parametrization of hadron observables. With our preferable universal value of the SU(3)-symmetry parameter ${\alpha }_D=D/F+D=.58$, taken for both magnetic moments and axial-vector constants entering into the semi-leptonic baryon decays, we obtain the following values for moments $\Delta q$ of the spin-dependent structure function of the proton: $\Delta u\simeq .84(.82),\Delta d\simeq -.42(-.44),\Delta s=-.22\pm .05(-.10\pm .03)$, where the values in parentheses correspond to the widely used "standard" value of ${\alpha }_D^{axial}=.63$. The estimations of the strange sea contributions to the nucleon magnetic moments and rms are also presented.

Comments: 8 pages, Latex, no figures, Talk given at the VII-th International Workshop on High Energy Spin Physics, Dubna, 7-12 July 1997, to be published in Proceedings