Bottom-Hadron Mass Splittings from Static-Quark Action on 2+1-Flavor Lattices

We calculate bottom-hadron mass splittings with respect to $B_d$ and $\Lambda_b$ using full QCD with 2+1 flavors of dynamical Kogut-Susskind sea quarks and domain-wall valence quarks along with a static heavy quark. Our lattices have spatial volume of $(2.5{fm})^3$ with lattice spacing about 0.124 fm and a range of pion masses as low as 291 MeV. Our results are in agreement with experimental observations and other lattice calculations within our statistical and systematic errors. In particular, we find the mass of the $\Omega_b$ to be consistent with the recent CDF measurement. We also predict the mass for the as yet unobserved $\Xi^\prime_b$ to be 5955(27) MeV.