Measurement of the branching fraction of $B^+ \to \tau^+ \nu_\tau$ decays with the semileptonic tagging method and the full Belle data sample

TL;DR

This paper measures the branching fraction of $B^+ o au^+ u_ au$ decays using the full Belle dataset, employing semileptonic tagging to improve accuracy, and finds results consistent with the Standard Model.

Contribution

It presents a new measurement of the $B^+ o au^+ u_ au$ branching fraction using the full Belle data sample with a semileptonic tagging method, enhancing previous precision.

Findings

Branching fraction measured as (1.25 ± 0.28 (stat.) ± 0.27 (syst.)) × 10^{-4}

Result agrees with Standard Model predictions

Utilizes the full Belle dataset of 772 million $Bar{B}$ pairs

Abstract

We report a measurement of the branching fraction of $B^+ \to \tau^+ \nu_\tau$ decays using a data sample of $772 \times 10^6 B \bar{B}$ pairs, collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We reconstruct the accompanying $B$ meson in a semileptonic decay and detect the $B^+ \to \tau^+ \nu_\tau$ candidate in the recoiling event. We obtain a branching fraction of ${\cal B}(B^+ \to \tau^+ \nu_\tau) = [1.25 \pm 0.28 ({\rm stat.}) \pm 0.27({\rm syst.})] \times 10^{-4}$. This result is in good agreement with previous measurements and the expectation from calculations based on the Standard Model.