The structure of the nucleon: baryons and pentaquarks

Abstract

In these lecture notes I discuss an algebraic model of baryons and pentaquarks, in particular a stringlike collective model is considered in which the radial excitations of baryons and pentaquarks are interpreted as rotations and vibrations of the strings. The algebraic structure of the model makes it possible to derive closed expressions for physical observables, such as masses and electromagnetic and strong couplings. The model is applied to the mass spectrum and magnetic moments of baryon resonances of the nucleon and delta families and to exotic baryons of the theta family. The ground pentaquark is predicted to have angular momentum and parity J(P)=1/2(-) and a small magnetic moment of 0.382 nuclear magnetons.