The quark model and b baryons

摘要

The recent observation at the Tevatron of E_ (uub and ddb) baryons within 2 MeV of the predicted Eb _ '1b splitting and of Ξ_b~- (dsb) baryons at the Tevatron within a few mega electron volts (MeV) of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of М(Ξ_b~-) = 5790-5800 MeV is reviewed and similar methods used to predict the masses of the excited states Ξ_Нb 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 Ξ_b-Ξ′_b mixing are small. For S-wave qqb states we predict M(Ω_b) = 6052.1 ± 5.6 MeV, M(Ω_b~*) = 6082.8 ± 5.6 MeV, and М( Ξ_b~0) = 5786.7 ± 3.0 MeV. For states with one unit of orbital angu_lar momentum between the b quark and the two light quarks we predict М(лb,з/2]) = 5929 ± 2 MeV, M(Ab[s/s]) = 5940 ± 2 MeV. M(Ξ_(b[1/2])) = 6106L 4 MeV, and M(Ξ_(b[3/2])) = 6115 L 4 MeV. Results are compared with those of other recent approaches.