$\tau$ lepton physics at Belle and Belle II

8 Jun 2026, 18:05
20m
Scuola Normale Superiore, Aula Dini, Palazzo del Castelletto (Pisa)

Scuola Normale Superiore, Aula Dini, Palazzo del Castelletto

Pisa

Via del Castelletto, 11, 56126 Pisa PI

Speaker

Yipu Liao

Description

The Belle and Belle II experiments have collected a $1.6~\mathrm{ab}^{-1}$ sample of $e^+e^-$ collision data at center-of-mass energies near the $\Upsilon(nS)$ resonances. This sample contains approximately 1.3 billion $e^+e^-\to \tau^+\tau^{-}$ events. We use the Belle and Run 1 Belle II data samples to search for lepton-flavor violating decays, presenting searches for the decays $\tau \to \mu\gamma$, $\tau \to \ell\eta$, $\tau\to \ell\pi^0$, and $\tau^-\to \ell^-\alpha$, where $\ell = e$ or $\mu$ and $\alpha$ is an invisible scalar particle. Using the Belle II $600~\mathrm{fb}^{-1}$ data sample we also present new measurements including the $C\!P$ asymmetry in $\tau \to K^0 \pi\nu$ decays, the $\tau$ lifetime, and branching fractions and spectral moments of $\tau$ decays to final states with strangeness.

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Author

Yipu Liao

Co-author

Steven Robertson (University of Alberta)

Presentation materials