Exotic and nonexotic magnetic transitions in the context of the SELEX and GRAAL experiments

Abstract

We calculate magnetic transition moments in the chiral quark-soliton model, with explicit SU(3)-symmetry breaking taken into account. The dynamical model parameters are fixed by experimental data for the magnetic moments of the baryon octet and from the recent measurements of ${\ensuremath{\Theta}}^{+}$ mass. Known magnetic transition moments ${\ensuremath{\mu}}_{\ensuremath{\Lambda}\ensuremath{\Sigma}}$, ${\ensuremath{\mu}}_{N\ensuremath{\Delta}}$ are reproduced and predictions for other octet-decuplet and octet-antidecuplet transitions are given. In particular ${\ensuremath{\mu}}_{\ensuremath{\Sigma}{\ensuremath{\Sigma}}^{*}}$ recently constrained by SELEX is shown to be below $0.82{\ensuremath{\mu}}_{N}$. The recent GRAAL data on $\ensuremath{\eta}$ photoproduction off the nucleon are explained in terms of a new narrow antidecuplet neutronlike resonance.