Valerio Bertacchi

29 June 2023

Abstract: The Belle~II experiment at the SuperKEKB energy-asymmetric electron-positron collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. Belle~II collected a sample of $362~\mathrm{fb}^{-1}$ at the $\Upsilon(4S)$ resonance between 2019 and the 2022, with a maximum peak luminosity of $4.7~\cdot 10^{34}~\mathrm{cm}^{-2}s^{-1}$. We report the recent measurements which involve neutral current transitions in $B$ meson decays. In particular, we present the branching fractions measurements of the radiative decays $B\to K^*\gamma$ and the fully inclusive $B\to X_s\gamma$, the search for $B^+\to K^+\nu\overline \nu$ decays, the measurement of the branching fractions of $B\to J/\psi(\to \ell\ell)K$ and $B\to K^*\ell\ell$. We also present the future prospects and the expected improvements for all the listed measurements. Finally, we show the perspectives of the search for $B\to K^{*}\tau\tau$ and the searches of lepton flavor violating channels $B\to K^{(*)}\ell\ell'$, with $\ell=e, \mu, \tau$.

Keyword(s): Neutral Currents ; Electroweak penguins ; radiative decays ; Lepton Flavor Violation ; Lepton Flavor Universality
Note: Proceedings of the conference "New Frontiers in Lepton Flavor", Pisa, 2023. The relative talk is: BELLE2-TALK-CONF-2023-059