Lorentz Covariant Spin—Grouping of Baryon Resonances

Abstract

A well pronounced spin-grouping of baryon resonances to O(4) partial waves is found in baryon spectra and shown to be well interpreted in terms of Lorentz group representations of the type {1/2 + l′, 1/2 +l′} ⊗ [{1/2, 0} ⊕ {0, 1/2}] with l′ integer. In this way the relativistic description of finite dimensional resonance towers containing higher-spin states becomes possible. It is further argued that the nucleon excitations into the l′ = 1 and l′ = 2 multiplets are chiral phase transitions.