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ISSN - 14346044, EISSN - 14346052, European Physical Journal C, 2015, vol. 76, 7, p. -

Improved measurement of the absolute branching fraction of D<sup>+</sup> → K<sup>0</sup><inf>µ</inf><sup>+</sup><inf>νµ</inf>

Ablikim M., Achasov M. N., Ai X. C., Albayrak O., Albrecht M., Ambrose D. J., Amoroso A., An F. F., An Q., Bai J. Z., Baldini Ferroli R., Ban Y., Bennett D. W., Bennett J. V., Bertani M., Bettoni D., Bian J. M., Bianchi F., Boger E., Boyko I., 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 H. Y., Chen J. C., Chen M. L., Chen S., Chen S. J., Chen X., Chen X. R., Chen Y. B., Cheng H. P., Chu X. K., Cibinetto G., Dai H. L., Dai J. P., Dbeyssi A., Dedovich D., Deng Z. Y., Denig A., Denysenko I., Destefanis M., De Mori F., Ding Y., Dong C., Dong J., Dong L. Y., Dong M. Y., Dou Z. L., Du S. X., Duan P. F., Fan J. Z., Fang J., Fang S. S., Fang X., Fang Y., Farinelli R., Fava L., Fedorov O., Feldbauer F.

© The Author(s) 2016.By analyzing 2.93 fb-1 of data collected at √s = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D+ → K 0µ+νµ) = (8.72 ±0.07stat. ±0.18sys.) %, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D0 → K-µ+νµ), B(D+ → K 0e+νe), and the lifetimes of the D0 and D+ mesons with the value of B(D+ → K 0µ+νµ) measured in this work, we determine the following ratios of partial widths: Γ(D0 → K-µ+νµ)/Γ(D+ → K 0µ+νµ) = 0.963 ± 0.044 and Γ(D+ → K 0µ+νµ)/Γ(D+ → K 0e+νe) = 0.988±0.033. mechanisms with better accuracy. In addition, the improved B(D+ → K 0µ+νµ) can also be used to precisely determine the form factor f K+ (0) and the quark mixing matrix element |Vcs| from D semileptonic decays [3]. Previous measurements of B(D+ → K 0µ+νµ) come from MARKIII [4], FOCUS [5] and BESII [6]. In this paper, by analyzing 2.93 fb-1 of data [7,8] collected at the centerof- mass energy of √s = 3.773 GeV by the BESIII detector [9], we determine the absolute branching fraction of D+ → K 0µ+νµ. Throughout the paper, charge conjugation is implied.