Abstract
Using a dataset of of annihilation data collected with the BESIII detector at center-of-mass energies between 4178 and 4226 MeV, we have measured the absolute branching fraction of the leptonic decay via , and find , where the first uncertainty is statistical and the second is systematic. The precision is improved by a factor of 2 compared to the previous best measurement. Combining with from lattice quantum chromodynamics calculations or the from the CKMfitter group, we extract and , respectively. Combining our result with the world averages of and , we obtain the ratio of the branching fractions , which is consistent with the standard model prediction of lepton flavor universality.
- Received 4 June 2021
- Revised 26 August 2021
- Accepted 21 September 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.171801
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