Study of Exclusive $B \to \pi e^+ \nu_e$ Decays with Hadronic Full-event-interpretation Tagging in 189.3 fb$^{-1}$ of Belle II Data

Sumitted to PubDB: 2022-09-21

Category: Conference papers and plots, Visibility: Public

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Authors	Moritz Bauer, Pablo Goldenzweig, Nadia Toutounji, Kevin Varvell
Date	June 16, 2022
Belle II Number	BELLE2-CONF-PH-2022-008a
Abstract	We present a reconstruction of the semileptonic decays $B^0 \to \pi^- e^+ \nu_e$ and $B^+ \to \pi^0 e^+ \nu_e$ in a sample corresponding to 189.3 fb$^{-1}$ of Belle II data, using events where the partner $B$-meson is reconstructed from a large variety of hadronic channels via a tagging algorithm known as the full-event-interpretation. We determine the partial branching fractions in three bins of the squared momentum transfer to the leptonic system using fits to the distribution of the square of the missing mass. The partial branching fractions are summed to determine $\mathcal{B}(B^0 \to \pi^- e^+ \nu_e)$ = (1.43 $\pm$ 0.27(stat) $\pm$ 0.07(syst)) $\times 10^{-4}$ and $\mathcal{B}(B^+ \to \pi^0 e^+ \nu_e)$ = (8.33 $\pm$ 1.67(stat) $\pm$ 0.55(syst)) $\times 10^{-5}$. We extract a first Belle II measurement of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $\|V_{\mathrm{ub}}\|$, with $\|V_{\mathrm{ub}}\|$ = (3.88 $\pm$ 0.45) $\times 10^{-3}$.