The Quark Model and b Baryons

The recent observation at the Tevatron of Σ±b (uub and ddb) baryons within 2 MeV of the predicted Σb − Λb splitting and of Ξ−b (dsb) baryons at the Tevatron within a few MeV of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of M(Ξ−b ) = 5790 to 5800 MeV is reviewed and similar methods used to predict the masses of the excited states Ξ′b and Ξ∗b . The main source of uncertainty is the method used to estimate the mass difference mb −mc from known hadrons. We verify that corrections due to the details of the interquark potential and to Ξb–Ξ ′ b mixing are small. For S-wave qqb states we predict M(Ωb) = 6052.1± 5.6 MeV, M(Ω∗b) = 6082.8± 5.6 MeV, and M(Ξb) = 5786.7± 3.0 MeV. For states with one unit of orbital angular momentum between the b quark and the two light quarks we predict M(Λb[1/2]) = 5929 ± 2 MeV, M(Λb[3/2]) = 5940 ± 2 MeV, M(Ξb[1/2]) = 6106 ± 4 MeV, and M(Ξb[3/2]) = 6115 ± 4 MeV. Results are compared with those of other recent approaches. PACS codes: 14.20.Mr, 12.40.Yx, 12.39.Jh, 11.30.Hw