We report two new measurements for tests of lepton flavor universality between electrons and muons using semileptonic B decays with a data set of 189fb−1 collected at the Belle II experiment between 2019 and 2021. Firstly, we find a ratio of inclusive branching fractions at R(Xe/μ)≡B(B→Xe−νe)/B(B→Xμ−νμ)=1.007±0.009(stat.)±0.019(syst.). This inclusive measurement leads to the most precise universality test based on branching fractions. The measured R(Xe/μ) is consistent with the Standard-Model prediction. Secondly, we measure a comprehensive set of five angular asymmetries of B0→D∗+ℓ−νℓ decays and obtain agreements with the Standard Model for the measured asymmetries and their differences at a p-value above 13%. From both tests, no evidence of lepton universality violation is found.
@article{arxiv.2307.09541,
title = {Belle II results related to $b \to c$ anomalies},
author = {Kazuki Kojima},
journal= {arXiv preprint arXiv:2307.09541},
year = {2023}
}
Comments
Contribution to the 2023 Electroweak session of the 57th Rencontres de Moriond, https://docs.belle2.org/record/3744