Measurement of $B^+\to\tau^+\nu_\tau$ branching fraction with a hadronic tagging method at Belle II
| Abstract | We present a measurement of the branching fraction of $B^+\to\tau^+\nu_\tau$ decays using $(387\pm6)\times 10^6$ $\Upsilon(4S)$ collected between 2019 and 2022 with the Belle II detector at the SuperKEKB $e^+e^-$ collider. We reconstruct the accompanying $B^-$ meson using the hadronic tagging method, while $B^+\to\tau^+\nu_\tau$ candidates are identified in the recoil. We find evidence for $B^+\to\tau^+\nu_\tau$ decays at 3.0 standard deviations, including systematic uncertainties. The measured branching fraction is $\mathcal{B}(B^+\to\tau^+\nu_\tau) = [1.24 \pm 0.41 (\text{stat.}) \pm 0.19 (\text{syst.})] \times 10^{-4}$. |
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| Tags | Run 1 |
| Working group | Semileptonic and Missing Energy Decay |
| Principal authors | @ Michele Aversano, Guglielmo De Nardo, Giovanni Gaudino, Toru Iijima, Mario Merola |
| Reference | published in PRD |
| Document | BELLE2-PUB-DRAFT-2024-013 |
| Links | arXiv:2502.04885, Inspire, |