Excited-state spectroscopy of triply bottom baryons from lattice QCD

The spectrum of baryons containing three b quarks is calculated in nonperturbative QCD, using the lattice regularization. The energies of ten excited bbb states with J(P) = 1/2(+), 3/2(+), 5/2(+), 7/2(+), 1/2(-), and 3/2(-) are determined with high precision. A domain-wall action is used for the up, down, and strange quarks, and the bottom quarks are implemented with nonrelativistic QCD. The computations are done at lattice spacings of a approximate to 0.11 fm and a approximate to 0.08 fm, and the results demonstrate the improvement of rotational symmetry as a is reduced. A large lattice volume of (2.7 fm)(3) is used, and extrapolations of the bbb spectrum to realistic values of the light sea-quark masses are performed. All spin-dependent energy splittings are resolved with total uncertainties of order 1 MeV, and the dependence of these splittings on the couplings in the nonrelativistic QCD action is analyzed.