Speaker
李文哲 (Wenzhe Li)
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. We present 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. In addition, we present results of searches for $\chi_{bJ} \to e \mu, e \tau$, and $\mu \tau$, as well as $B \to K \ell \tau$ ($\ell = e, \mu$).