Andrea Fodor

24 February 2021

Abstract: The semileptonic $B$ meson decays of the type $B \to X_u \ell \nu$ are important for measuring the $|V_{ub}|$ CKM matrix element. Recent measurements of inclusive $B \to X_u e \nu_e$ and hadronic-tagged $B^0 \to \pi^- \ell^+ \nu$ from the Belle II experiment are presented. The results are obtained using the data collected at Belle II between March 2019 and March 2020, with the total luminosity of 37.8~fb$^{-1}$. These preliminary measurements are used to validate the detector and reconstruction software performance. The measured preliminary branching fraction of $B^0 \to \pi^- \ell^+ \nu$, equal to $(1.58 \pm 0.43_{\textrm{stat}} \pm 0.07_{\textrm{sys}})\cdot 10^{-4}$, is in agreement with the world average.

Note: BEAUTY2020 proceedings