Abstract
By analyzing of annihilation data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we determine the branching fraction of the leptonic decay , with , to be . We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element and the decay constant to be , using the known values of the and masses as well as the lifetime, together with our branching fraction measurement. Combining the value of obtained from a global fit in the standard model and from lattice quantum chromodynamics, we obtain and . Using the branching fraction of , we obtain the ratio of the branching fractions , which is consistent with the standard model prediction of lepton flavor universality.
- Received 17 May 2021
- Accepted 7 July 2021
DOI:https://doi.org/10.1103/PhysRevD.104.032001
Published by the American Physical Society under the terms of the 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.
Published by the American Physical Society