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 Σ ΔI=2 isospin mass splittings for the heavy Σ baryon systems approach finite but undetermined values, independent of the spin of the Σ baryon and the flavor of the heavy quark. We propose, with supporting evidence, that the flavor-spin symmetries for those processes, with the isoscalar quark as a spectator, can be extended to all isoscalar quarks and thus overlap with the low-energy SU(6) symmetry through the strange quark. By interpolating between the flavor-spin symmetries at the heavy quark masses and the strange quark mass we determine these interesting properties of the heavy Σ baryons from the available low-energy data. We also discuss the interesting pattern of theoretical calculations and the experimental conflict on the Σc ΔI=2 isospin mass splitting. © 1996 The American Physical Society.