Using e+e- annihilation data of 2.93 fb-1 collected at center-of-mass energy s=3.773 GeV with the BESIII detector, we measure the absolute branching fraction of D0→K-μ+νμ with significantly improved precision: BD0→K-μ+νμ=(3.413±0.019stat±0.035syst)%. Combining with our previous measurement of BD0→K-e+νe, the ratio of the two branching fractions is determined to be BD0→K-μ+νμ/BD0→K-e+νe=0.974±0.007stat±0.012syst, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. A study of the ratio of the two branching fractions in different four-momentum transfer regions is also performed, and no evidence for lepton flavor universality violation is found with current statistics. Taking inputs from global fit in the standard model and lattice quantum chromodynamics separately, we determine f+K(0)=0.7327±0.0039stat±0.0030syst and |Vcs|=0.955±0.005stat±0.004syst±0.024LQCD.
Bibliographical noteFunding Information:
The BESIII collaboration thanks the staff of BEPCII and the IHEP computing center for their strong support. This work is supported in part by National Key Basic Research Program of China under Contract No. 2015CB856700; National Natural Science Foundation of China (NSFC) under Contracts No. 11305180, No. 11775230, No. 11235011, No. 11335008, No. 11425524, No. 11625523, and No. 11635010; the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; the CAS Center for Excellence in Particle Physics (CCEPP); Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1632109, No. U1332201, No. U1532257, and No. U1532258; CAS under Contracts No. KJCX2-YW-N29, No. KJCX2-YW-N45, and No. QYZDJ-SSW-SLH003; 100 Talents Program of CAS; National 1000 Talents Program of China; INPAC and Shanghai Key Laboratory for Particle Physics and Cosmology; German Research Foundation DFG under Contracts No. Collaborative Research Center CRC 1044, No. FOR 2359; Instituto Nazionale di Fisica Nucleare, Italy; Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) under Contract No. 530-4CDP03; Ministry of Development of Turkey under Contract No. DPT2006K-120470; National Science and Technology fund; The Swedish Research Council; U.S. Department of Energy under Contracts No. DE-FG02-05ER41374, No. DE-SC-0010118, No. DE-SC-0010504, and No. DE-SC-0012069; University of Groningen (RuG) and the Helmholtzzentrum fuer Schwerionenforschung GmbH (GSI), Darmstadt; WCU Program of National Research Foundation of Korea under Contract No. R32-2008-000-10155-0.