Eberhard . KLEMPT (Université Bonn)
The Particle Data Group lists 100 baryon resonances, 50 of them are established and have known spin and parity. Due to the absence of spin-orbit forces the intrinsic orbital angular momentum of a resonance can mostly be identified ; it turns out to be the variable which determines baryon excitation energy w.r.t. the ground state of all decuplet baryons and all baryons belonging to a spin quartet. Octet and singlet baryons undergo a shift in mass square proportional to the fraction in the wave function which is antisymmetric in spin and flavor. A discussion of the symmetry properties of baryonic wave functions suggests a natural explanation of the absence of a large number of resonances.
