Search for decays at the Belle experiment

Sibidanov, A.*; 谷田 聖; Belle Collaboration*; 他187名*

Physical Review Letters, 121(3), p.031801_1 - 031801_8, 2018/07

AA2018-0589.pdf:0.39MB

https://doi.org/10.1103/PhysRevLett.121.031801

We report the result of a search for the decay . The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic -meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of or a frequentist 90% confidence level interval on the branching fraction of . This result is obtained from a 711 fb data sample that contains pairs, collected near the resonance with the Belle detector at the KEKB asymmetric-energy collider.