The and 0 Leptonic Widths, a b and mb from full lattice QCD

rst time. We use radiatively-improved NRQCD 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 nd ( ! e + e ) = 1.19(11) keV and ( 0 ! e + e ) = 0.69(9) keV, both in good agreement with experiment. 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 (e + e ! hadrons) and calculate the b-quark piece of the hadronic vacuum polarisation contribution to the anomalous magnetic moment of the muon, a b = 0:271(37) 10 10 . Finally we determine the b-quark mass, obtaining in the MS scheme, mb(mb;nf = 5) = 4.196(23) GeV, the most accurate result from lattice QCD to date.