2,005 research outputs found

    The B(s)D(s)lνB_{(s)} \to D_{(s)}l\nu Decay with Highly Improved Staggered Quarks and NRQCD

    Full text link
    We report on progress of a lattice QCD calculation of the BDlνB\to Dl\nu and BsDslνB_s\to D_s l\nu semileptonic form factors. We use a relativistic staggered action (HISQ) for light and charm quarks, and an improved non-relativistic (NRQCD) action for bottom, on the second generation MILC ensembles.Comment: Presented at Lattice 2017, the 35th International Symposium on Lattice Field Theory at Granada, Spain (18-24 June 2017

    Υ and Υ′ leptonic widths, abμ, and mb from full lattice QCD

    Get PDF
    We determine the decay rate to leptons of the ground-state ϒ meson and its first radial excitation in lattice QCD for the first time. We use radiatively improved nonrelativistic QCD for the b quarks and include u, d, s and c quarks in the sea with u=d masses down to their physical values. We find Γðϒ → eþe−Þ ¼ 1.19ð11Þ keV and Γðϒ0 → eþe−Þ ¼ 0.69ð9Þ keV, both in good agreement with experimental results. The decay constants we obtain are included in a summary plot of meson decay constants from lattice QCD given in the Conclusions. We also test time moments of the vector current-current correlator against values determined from the b-quark contribution to σðeþe− → hadronsÞ and calculate the b-quark piece of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, ab μ ¼ 0.271ð37Þ × 10−10. Finally we determine the b-quark mass, obtaining in the MS scheme, ¯ m¯ bðm¯ b; nf ¼ 5Þ ¼ 4.196ð23Þ GeV, the most accurate result from lattice QCD to date

    B-meson decay constants: a more complete picture from full lattice QCD

    Get PDF
    We extend the picture of BB-meson decay constants obtained in lattice QCD beyond those of the BB, BsB_s and BcB_c to give the first full lattice QCD results for the BB^*, BsB^*_s and BcB^*_c. We use improved NonRelativistic QCD for the valence bb quark and the Highly Improved Staggered Quark (HISQ) action for the lighter quarks on gluon field configurations that include the effect of u/du/d, ss and cc quarks in the sea with u/du/d quark masses going down to physical values. For the ratio of vector to pseudoscalar decay constants, we find fB/fBf_{B^*}/f_B = 0.941(26), fBs/fBsf_{B^*_s}/f_{B_s} = 0.953(23) (both 2σ2\sigma less than 1.0) and fBc/fBcf_{B^*_c}/f_{B_c} = 0.988(27). Taking correlated uncertainties into account we see clear indications that the ratio increases as the mass of the lighter quark increases. We compare our results to those using the HISQ formalism for all quarks and find good agreement both on decay constant values when the heaviest quark is a bb and on the dependence on the mass of the heaviest quark in the region of the bb. Finally, we give an overview plot of decay constants for gold-plated mesons, the most complete picture of these hadronic parameters to date.Comment: 20 pages, 9 figures. Minor updates to the discussion in several places and some additional reference

    Diffusive hidden Markov model characterization of DNA looping dynamics in tethered particle experiments

    Get PDF
    In many biochemical processes, proteins bound to DNA at distant sites are brought into close proximity by loops in the underlying DNA. For example, the function of some gene-regulatory proteins depends on such DNA looping interactions. We present a new technique for characterizing the kinetics of loop formation in vitro, as observed using the tethered particle method, and apply it to experimental data on looping induced by lambda repressor. Our method uses a modified (diffusive) hidden Markov analysis that directly incorporates the Brownian motion of the observed tethered bead. We compare looping lifetimes found with our method (which we find are consistent over a range of sampling frequencies) to those obtained via the traditional threshold-crossing analysis (which can vary depending on how the raw data are filtered in the time domain). Our method does not involve any time filtering and can detect sudden changes in looping behavior. For example, we show how our method can identify transitions between long-lived, kinetically distinct states that would otherwise be difficult to discern

    Reporting and design elements of audit and feedback interventions: a secondary review

    Get PDF
    BACKGROUND: Audit and feedback (A&F) is a frequently used intervention aiming to support implementation of research evidence into clinical practice with positive, yet variable, effects. Our understanding of effective A&F has been limited by poor reporting and intervention heterogeneity. Our objective was to describe the extent of these issues. METHODS: Using a secondary review of A&F interventions and a consensus-based process to identify modifiable A&F elements, we examined intervention descriptions in 140 trials of A&F to quantify reporting limitations and describe the interventions. RESULTS: We identified 17 modifiable A&F intervention elements; 14 were examined to quantify reporting limitations and all 17 were used to describe the interventions. Clear reporting of the elements ranged from 56% to 97% with a median of 89%. There was considerable variation in A&F interventions with 51% for individual providers only, 92% targeting behaviour change and 79% targeting processes of care, 64% performed by the provider group and 81% reporting aggregate patient data. CONCLUSIONS: Our process identified 17 A&F design elements, demonstrated gaps in reporting and helped understand the degree of variation in A&F interventions
    corecore