Hadron Spectrum Collaboration)We present the first light-hadron spectroscopy on a set of N f = 2 + 1 dynamical, anisotropic lattices. A convenient set of coordinates that parameterize the two-dimensional plane of light and strange-quark masses is introduced. These coordinates are used to extrapolate data obtained at the simulated values of the quark masses to the physical light and strange-quark point. A measurement of the Sommer scale on these ensembles is made, and the performance of the hybrid Monte Carlo algorithm used for generating the ensembles is estimated.
Highly excited states for isospin 1 2 baryons are calculated for the first time using lattice QCD with two flavors of dynamical quarks. Anisotropic lattices are used with two pion masses, mπ = 416(36) MeV and 578(29) MeV. The lowest four energies are reported in each of the six irreducible representations of the octahedral group at each pion mass. The lattices used have dimensions 24 3 ×64, spatial lattice spacing as ≈ 0.11 fm and temporal lattice spacing at = 1 3 as. Clear evidence is found for a 5 2 − state in the pattern of negative-parity excited states. This agrees with the pattern of physical states and spin 5 2 has been realized for the first time on the lattice.
The energies of the excited states of the nucleon, Á, and are computed in lattice QCD, using two light quarks and one strange quark on anisotropic lattices. The calculation is performed at three values of the light quark mass, corresponding to pion masses m ¼ 392ð4Þ, 438(3), and 521(3) MeV. We employ the variational method with a large basis of interpolating operators enabling six energies in each irreducible representation of the lattice to be distinguished clearly. We compare our calculation with the low-lying experimental spectrum, with which we find reasonable agreement in the pattern of states. The need to include operators that couple to the expected multihadron states in the spectrum is clearly identified.
Progress in determining the spectrum of excited baryons and mesons in lattice QCD is described. Large sets of carefully-designed hadron operators have been studied and their effectiveness in facilitating the extraction of excited-state energies is demonstrated. A new method of stochastically estimating the low-lying effects of quark propagation is proposed which will allow reliable determinations of temporal correlations of single-hadron and multi-hadron operators.
Using samples of (5.93 ± 0.10) × 10 6 Υ(3S) decays and (9.11 ± 0.14) × 10 6 Υ(2S) decays collected with the CLEO detector, we report improved measurements of the branching fractions for the following five transitions: B(Υ(3S)→Υ(1S)π + π − ) = (4.46 ± 0.01 ± 0.13)%, B(Υ(2S)→Υ(1S)π + π − ) = (18.02 ± 0.02 ± 0.61)%, B(Υ(3S)→Υ(1S)π 0 π 0 ) = (2.24 ± 0.09 ± 0.11)%, B(Υ(2S)→Υ(1S)π 0 π 0 ) = (8.43±0.16±0.42)% and B(Υ(3S)→Υ(2S)π 0 π 0 ) = (1.82±0.09±0.12)%. In each case the first uncertainty reported is statistical, while the second is systematic.
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