English

Belle II results related to $b \to c$ anomalies

High Energy Physics - Experiment 2023-07-20 v1

Abstract

We report two new measurements for tests of lepton flavor universality between electrons and muons using semileptonic BB decays with a data set of 189 fb1189~\mathrm{fb}^{-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(BXeνe)/B(BXμνμ)=1.007±0.009(stat.)±0.019(syst.)R(X_{e/\mu}) \equiv \mathcal{B}(\overline{B} \rightarrow Xe^{-}\overline{\nu}_{e})/\mathcal{B}(\overline{B} \rightarrow X\mu^{-}\overline{\nu}_{\mu}) = 1.007 \pm 0.009 (\mathrm{stat.}) \pm 0.019 (\mathrm{syst.}). This inclusive measurement leads to the most precise universality test based on branching fractions. The measured R(Xe/μ)R(X_{e/\mu}) is consistent with the Standard-Model prediction. Secondly, we measure a comprehensive set of five angular asymmetries of B0D+ν\overline{B}^{0} \rightarrow {D^{*}}^{+}\ell^{-}\overline{\nu}_{\ell} decays and obtain agreements with the Standard Model for the measured asymmetries and their differences at a pp-value above 13%13\%. From both tests, no evidence of lepton universality violation is found.

Keywords

Cite

@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