Measurements of tau decays at Belle and Belle II

Sumitted to PubDB: 2025-05-15

Category: Talk, Visibility: Latest Version Public

Authors	Vladimir Savinov
Date	2025-05-19
Belle II Number	BELLE2-TALK-2025-074
Abstract	The Belle and Belle~II experiments have collected a $1.4~\mathrm{ab}^{-1}$ sample of $e^+e^-$ collision data at centre-of-mass energies near the $\Upsilon(nS)$ resonances. This sample contains approximately 1.3 billion $e^+e^-\to \tau^+\tau^{-}$ events, which we use to search for lepton-flavour violating decays. We present searches for $\tau-\to \mu^-\mu^-\mu^+$, $\tau^-\to\Lambda\pi^-$, and $\tau^-\to \bar{\Lambda}\pi^-$. We also present world leading measurements of the $\tau$ mass and lepton-flavour universality in $\tau\to\ell\nu\bar{\nu}$ decay, where $\ell$ is an electron or a muon.
Conference	Phenomenology 2025 Symposium (PHENO2025) (start: 2025-05-19)