Baryon Mass Spectra and Baryon Couplings

Abstract
General intermultiplet mass formulas between the decuplet and octet baryons are derived, based on the chiral SU(3)SU(3) charge algebra and the asymptotic SU(3) symmetry imposed only on the charge operator VK which is the SU(3) raising or lowering operator in the symmetry limit. In the absence of particle mixing, the formulas take on a simple form and are useful as a first guide in deducing baryon mass spectra. Inclusion of particle mixing is possible. The formulas imply that the equal squared-mass spacings of decuplet states (δa)2 (a specifies the quantum numbers of the a decuplet) are universal [i.e., (δa)2=const] and, furthermore, equal to the universal spacings of the Ξ and Σ members of any octet baryons. In the case of the usual ½+ and 32+ baryons, the formulas coincide with the well-known SU(6) mass formula. Broken-SU(3) sum rules (in the absence of mixing) for general transitions of the form (octetbaryon)(octetbaryon)+π (or l+ν¯) are also obtained. In particular, the strong decays, 5212++π and 52+12++π, are discussed in detail. The sum rules, in general, give rise to significant SU(3)-breaking effects. However, for the familiar axial-vector 12+12++l+ν¯ transitions, our broken-SU(3) sum rules assume the same forms as satisfied by the hypothetical exact SU(3) couplings. This justifies the use of the original Cabibbo analysis [in broken-SU(3) symmetry] in determining the value of the axial-vector Cabibbo angle.