Abstract
We present the first measurement of the ratio of branching fractions of inclusive semileptonic -meson decays, , a precision test of electron-muon universality, using data corresponding to from electron-positron collisions collected with the Belle II detector. In events where the partner meson is fully reconstructed, we use fits to the lepton momentum spectra above to obtain , which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.
- Received 25 January 2023
- Revised 3 May 2023
- Accepted 11 May 2023
DOI:https://doi.org/10.1103/PhysRevLett.131.051804
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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
Physics Subject Headings (PhySH)
synopsis
Standard Model Stays Strong for Leptons
Published 2 August 2023
New data from observations of B-meson decay again vindicate the standard model of particle physics.
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