Search for lepton flavor-violating decay modes $B^0 \to K^{\ast 0}\tau^\pm\ell^\mp$ ($\ell = e,\mu$) with hadronic B-tagging at Belle and Belle II

The Belle-II & Belle collaborations Adachi, I. ; Ahn, Y. ; Aihara, H. ; et al.
Belle II preprint: 2025-014, 2025.
Inspire Record 2920672 DOI 10.17182/hepdata.159492

We present the results of a search for the charged-lepton-flavor violating decays $B^0 \rightarrow K^{*0}\tau^\pm \ell^{\mp}$, where $\ell^{\mp}$ is either an electron or a muon. The results are based on 365 fb$^{-1}$ and 711 fb$^{-1}$ datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic $B$-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed $B$ meson. We find no evidence for $B^0 \rightarrow K^{*0}\tau^\pm \ell^{\mp}$ decays and set upper limits on the branching fractions in the range of $(2.9-6.4)\times10^{-5}$ at 90% confidence level.

72 data tables

$M_{\tau}$ distribution in signal region, (OS$e$, Belle)

$M_{\tau}$ distribution in signal region, (OS$e$, Belle II)

$M_{\tau}$ distribution in signal region, (OS$\mu$, Belle)

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