EXTENDED ISOSCALAR-FLAVOR-SPIN SYMMETRIES FOR BARYONS WITH A SINGLE SPECTATOR ISOSCALAR QUARK

The flavor-spin symmetries of heavy quark effective theory imply that in the infinite heavy quark mass limit the magnetic moments, radiative decay rates, single pion emission decay rates, and the Sigma Delta I = 2 isospin mass splittings for the heavy Sigma baryon systems approac h finite but undetermined values, independent of the spin of the Sigma baryon and the flavor of the heavy quark. We propose, with supporting evidence, that the flavor-spin symmetries for those processes, with t he isoscalar quark as a spectator, can be extended to all isoscalar qu arks and thus overlap with the low-energy SU(6) symmetry through the s trange quark. By interpolating between the flavor-spin symmetries at t he heavy quark masses and the strange quark mass we determine these in teresting properties of the heavy Sigma baryons from the available low -energy data. We also discuss the interesting pattern of theoretical c alculations and the experimental conflict on the Sigma(c) Delta I = 2 isospin mass splitting.