Abstract
We present an analysis of the exclusive decay, where represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The study exploits the full data sample collected by the Belle detector, corresponding to of integrated luminosity. Events are selected by fully reconstructing one meson in hadronic decay modes, subsequently determining the properties of the other meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of , where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.
- Received 19 May 2020
- Accepted 27 April 2021
DOI:https://doi.org/10.1103/PhysRevD.103.112001
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