ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2014, vol. 89, p. -
Precision measurements of B (D+ →μ+νμ), the pseudoscalar decay constant fD+, and the quark mixing matrix element |Vcd |
© 2013 American Physical Society. We report a measurement of the branching fraction B(D+→μ+νμ)= [3.71±0.19(stat)±0.06(sys)]×10-4 based on 2.92fb-1 of data accumulated at s=3.773GeV with the BESIII detector at the BEPCII collider. This measurement, in conjunction with the Cabibbo-Kobayashi-Maskawa matrix element |Vcd| determined from a global Standard Model fit, implies a value for the weak decay constant fD+=(203.2±5.3±1.8)MeV. Additionally, using this branching fraction measurement together with a lattice QCD prediction for fD+, we find |Vcd|=0.2210±0.0058±0.0047. In either case, these are the most precise results for these quantities to date.