Measurements of $|V_{cb}|$ and $|V_{ub}|$ from Belle and Belle II

Abstract

This proceeding summarizes recent measurements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{cb}|$ and $|V_{ub}|$ at the Belle and Belle~II experiments. It provides insights derived from both exclusive and inclusive determinations. Preliminary results from Belle~II are discussed, focusing on $B^0\to D^{*-}\ell^+ \nu$ and $B^{0} \to \pi^{-} \ell^{+} \nu$ utilizing $189 \, \mathrm{fb}^{-1}$ data collected at the $\Upsilon(4S)$ resonance. This reveals the derived branching fractions and $|V_{xb}|$. The shape measurement of $B \to D^{*} \ell \nu$ at Belle extracted $|V_{cb}|$ employing new lattice-QCD calculations as input and provided additional tests on the universality of light lepton flavors. In the realm of inclusive decay, the measurement for $|V_{ub}|$ and the differential spectra of $B \to X_{u} \ell \nu$ decays have been performed. This presentation also encapsulates the new analyses of $|V_{ub}|^{\mathrm{excl}}/|V_{ub}|^{\mathrm{incl}}$ and $|V_{ub}|^{\mathrm{incl}}/|V_{cb}|^{\mathrm{incl}}$ ratios.