N and Delta Resonances in the Rigid Quark-Diquark Vibrator
  A nearest-neighbor analysis of light flavor baryon mass spectra reveals striking degeneracy patterns- narrow mass bands populated by series of parity twins of steadily increasing spins. Each series terminates by an unpaired resonance of the highest spin in the group. We trace back such degenerate series of resonances (to be termed "mega states") to internal baryon structure dominated by a quark -(rigid di-quark) configuration. Nucleon and Delta spectra are, surprisingly enough, exact replicas to each other in the sense that each of them features three mega states of equal quantum numbers. We fit positions and splittings of the observed mega states by an algebraic Hamiltonian which translates into a potential that is a combination of Coulomb- and Morse like potentials and predict few more such degenerate series to be observed by the TJNAF missing resonance program. Finally, we explore consequences of the model for some electrodynamic properties of the spectra. 
M. Kirchbach