Test of Lepton-Flavor Universality in B→K*ℓ+ℓ− Decays at Belle

Le résumé fourni par la source

We present a measurement of ${R}_{{K}^{*}}$, the branching fraction ratio $\mathcal{B}(B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})/\mathcal{B}(B\ensuremath{\rightarrow}{K}^{*}{e}^{+}{e}^{\ensuremath{-}})$, for both charged and neutral $B$ mesons. The ratio for the charged case ${R}_{{K}^{*+}}$ is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass ${q}^{2}$. The analysis is based on a data sample of $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, containing $772\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }B\overline{B}$ events, recorded at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. The obtained results are consistent with standard model expectations.

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