Update of Heavy Baryon Mass Predictions

Predictions of unknown heavy baryon masses based on an expansion in 1/mQ, 1/Nc and SU(3) breaking are updated to take into account a recent measurement of the Σc mass. Values are given for the two remaining unknown charm baryon masses Ξc and Ω ∗ c and the seven unknown bottom baryon masses Ξb, Σb, Ξ ′ b, Ωb, Σ ∗ b , Ξ ∗ b and Ω ∗ b . The spectrum of baryons containing a single charm or bottom quark recently has been analyzed in an expansion in 1/mQ, 1/Nc and SU(3) flavor breaking [1]. The analysis of Ref. [1] yields a hierarchy of mass relations among heavy quark baryons, as well as additional relations between heavy baryon mass splittings and mass splittings of the octet and decuplet baryons. From this analysis, it is possible to predict the unknown charm and bottom baryon masses to varying accuracies, where the errors on the predicted values reflect both experimental errors of measured baryon masses and the expected theoretical accuracies of the mass relations. Recently, a very precise measurement of the Σc mass has been reported by CLEO [3]. The most precise flavor-27 mass relations [2,1] of the charm baryons determine Ξc and (Σc +Ω ∗ c), but not Σ ∗ c and Ω ∗ c separately. Given the Σ ∗ c mass, it is possible to pin down the Ωc mass. With the entire charm baryon spectrum determined rather precisely, prediction of the bottom baryon spectrum from the charm baryon spectrum is improved. The mass Alfred P. Sloan Fellow. National Science Foundation Young Investigator.