Evidence for B- -> tau- nu_tau-bar with a Hadronic Tagging Method Using the Full Data Sample of Belle

TL;DR

This paper reports the first evidence for the decay B- -> tau- nu_tau-bar using the full Belle dataset, employing a hadronic tagging method to measure its branching fraction with a significance of 3.0 sigma.

Contribution

It provides the first evidence for B- -> tau- nu_tau-bar decay using a full data sample and a hadronic tagging approach, measuring its branching fraction.

Findings

Evidence for B- -> tau- nu_tau-bar with 3.0 sigma significance

Measured branching fraction: (0.72^{+0.27}_{-0.25} (stat) +/- 0.11 (syst)) x 10^-4

Utilized the full Belle dataset of 772 million BBbar pairs

Abstract

We measure the branching fraction of B- -> tau- nu_tau-bar using the full Upsilon(4S) data sample containing 772*10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. Events with BBbar pairs are tagged by reconstructing one of the B mesons decaying into hadronic final states, and B- -> tau- nu_tau-bar candidates are detected in the recoil. We find evidence for B- -> tau- nu_tau-bar with a significance of 3.0 standard deviations including systematic errors and measure a branching fraction B(B- -> tau- nu_tau-bar) = [0.72^{+0.27}_{-0.25}(stat) +/- 0.11(syst)] * 10^-4.