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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 |

Ablikim M., Achasov M. N., Ai X. C., Albayrak O., Ambrose D. J., An F. F., An Q., Bai J. Z., Baldini Ferroli R., Ban Y., Bennett J. V., Bertani M., Bian J. M., Boger E., Bondarenko O., Boyko I., Braun S., Briere R. A., Cai H., Cai X., Cakir O., Calcaterra A., Cao G. F., Cetin S. A., Chang J. F., Chelkov G., Chen G., Chen H. S., Chen J. C., Chen M. L., Chen S. J., Chen X., Chen X. R., Chen Y. B., Cheng H. P., Chu X. K., Chu Y. P., Cronin-Hennessy D., Dai H. L., Dai J. P., Dedovich D., Deng Z. Y., Denig A., Denysenko I., Destefanis M., Ding W. M., Ding Y., Dong C., Dong J., Dong L. Y., Dong M. Y., Du S. X., Fan J. Z., Fang J., Fang S. S., Fang Y., Fava L., Feng C. Q., Fu C. D., Fu J. L., Fuks O., Gao Q., Gao Y., Geng C., Goetzen K., Gong W. X., Gradl W., Greco M., Gu M. H., Gu Y. T., Guan Y. H., Guo A. Q., Guo L. B., Guo T., Guo Y. P., Guo Y. P., Han Y. L., Harris F. A., He K. L., He M., He Z. Y., Held T., Heng Y. K., Hou Z. L., Hu C., Hu H. M., Hu J. F., Hu T., Huang G. M., Huang G. S., Huang J. S., Huang L., Huang X. T.

© 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.