Precision measurements of B(D+ -> mu(+)nu(mu)), the pseudoscalar decay constant fD+, and the quark mixing matrix element vertical bar V-cd vertical bar

We report a measurement of the branching fractionB(D+ -> mu(+)nu(mu)) = [3.71 +/- 0.19(stat) +/- 0.06(sys)] x 10(-4) based on 2.92 fb(-1) of data accumulated at root s = 3.773 GeV with the BESIII detector at the BEPCII collider. This measurement, in conjunction with the Cabibbo-Kobayashi-Maskawa matrixelement vertical barV-cd vertical bardetermined from a global Standard Model fit, implies a value for the weak decay constant f(D+) = (203.2 +/- 5.3 +/- 1.8) MeV. Additionally, using this branching fractionmeasurement together with a lattice QCDprediction for f(D+), we find vertical barV-cd vertical bar0.2210 +/- 0.0058 +/- 0.0047. In either case, these are the most precise results for these quantities to date.