Study of the semileptonic decay ?c+ ? ?e+?e

The study of the Cabibbo-favored semileptonic decay ?c+??e+?e is reported using a 4.5 fb-1 data sample of e+e- annihilations collected at center-of-mass energies ranging from 4.600 GeV to 4.699 GeV with the BESIII detector at the BEPCII collider. The branching fraction of the decay is measured to be B(?c+??e+?e)=(3.56±0.11stat±0.07syst)%, which is the most precise measurement to date. Furthermore, we perform an investigation of the internal dynamics in ?c+??e+?e. We provide the first direct comparisons of the differential decay rate and form factors with those predicted from lattice quantum chromodynamics (LQCD) calculations. Combining the measured branching fraction with a q2-integrated rate predicted by LQCD, we determine |Vcs|=0.936±0.017B±0.024LQCD±0.007??c. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.