Phenomenology with Lattice NRQCD b Quarks

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The HPQCD collaboration has used radiatively-improved NonRelativistic QCD (NRQCD) for b quarks in bottomonium to determine the decay rate of Υ and Υ′ mesons to leptons in lattice QCD. Using time-moments of vector bottomonium current-current correlators, we are also able to determine the b quark mass in the MS scheme. We use the same NRQCD b quarks and Highly Improved Staggered Quark (HISQ) light quarks -- with masses down to their physical values -- to give a complete picture of heavy-light meson decay constants including those for vector mesons. We also study the semileptonic B→πℓν decay at zero recoil to show that lattice QCD is consistent with the soft pion theorem for this decay: f₀(q²max)=fB/fπ in the massless pion limit. Finally, we present preliminary results for the Bc → ηc ℓ ν semileptonic decay form factors. This is a showcase for the comparison of results for NRQCD b quarks with those from HISQ b quarks (both with HISQ c quarks). We give the first 3-point results from our `heavy HISQ' programme, which will allow us to improve the normalisation of NRQCD-HISQ currents for other calculations.