Abstract
We measure the tau-to-light-lepton ratio of inclusive -meson branching fractions , where indicates an electron or muon, and thereby test the universality of charged-current weak interactions. We select events that have one fully reconstructed meson and a charged lepton candidate from of electron-positron collision data collected with the Belle II detector. We find , in agreement with standard-model expectations. This is the first direct measurement of .
- Received 14 November 2023
- Accepted 19 April 2024
DOI:https://doi.org/10.1103/PhysRevLett.132.211804
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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