2023/05/08 by F. Abudinén, Belle II Collaboration, I. Adachi +673
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.2305.04759
openalex publication_date 2023/05/08 · openalex created_date 2023/05/10 · openalex updated_date 2026/08/01
We report a search for lepton-flavor-violating decays τ- → ℓ- ϕ (ℓ- =e-,μ-) at the Belle II experiment, using a sample of electron-positron data produced at the SuperKEKB collider in 2019-2021 and corresponding to an integrated luminosity of 190 fb-1. We use a new untagged selection for e+e- → τ+τ- events, where the signal τ is searched for as a neutrinoless final state of a single charged lepton and a ϕ meson and the other τ is not reconstructed in any specific decay mode, in contrast to previous measurements by the BaBar and Belle experiments. We find no evidence for τ- → ℓ- ϕ decays and obtain upper limits on the branching fractions at 90% confidence level of 23 × 10-8 and 9.7× 10-8 for τ- → e-ϕ and τ- → μ-ϕ, respectively