Arthur Thaller

26 August 2024
XIII International Conference on New Frontiers in Physics

Abstract: The Belle$~$II experiment has collected a $424~\mathrm{fb}^{-1}$ sample of $e^+e^-$ collision data at centre-of-mass energies near the $\Upsilon(nS)$ resonances. This sample contains 389 million $e^+e^-\to \tau^+\tau^{-}$ events, which we use for precision tests of the standard model. We present measurements of leptonic branching fractions, lepton-flavour universality between electrons and muons, the tau mass, and the Cabibbo-Kobayashi-Maskawa matrix element $V_{us}$.