Kenji Inami

05 August 2016
ICHEP 2016

Abstract: In this talk, we present studies of τ leptons at Belle and the prospects at SuperKEKB/Belle II. We evaluate the Michel parameters of τ leptonic decay using Belle’s full data sample. This measurement is important to reveal the Lorentz structure of τ leptonic decay, which includes not only the V−A interaction but also contributions from scalar, tensor and others that may arise from New Physics; this measurement tests lepton universality as well. We also measure branching fractions of τ decays into three charged pseudo-scalars and a tau neutrino using the full sample of Belle. In the previous analysis by Belle, some deviation from the existing measurements was seen for the branching fraction on τ→πππν mode; we expect to make this clear by our full analysis. The Belle~II experiment aims to record 50 ab−1 of data at the SuperKEKB energy-asymmetric e+e− collider. The anticipated high statistics data sample has excellent sensitivity to lepton flavor violating (LFV) τ lepton decays including τ→μγ, τ→μπ0/η and so on. Prospects and sensitivities for τ LFV at Belle~II will be presented.

Note: 10+5 minutes