000004045 001__ 4045
000004045 005__ 20240110023214.0
000004045 037__ $$aBELLE2-CONF-PROC-2023-049
000004045 041__ $$aeng
000004045 100__ $$aHenrik Junkerkalefeld
000004045 245__ $$aLepton universality tests and searches for new physics in charged current decays at Belle II
000004045 260__ $$a$$c2023-12-29
000004045 300__ $$a10
000004045 520__ $$aWe present recent tests of lepton universality as crucial probes of the Standard Model in semileptonic $B$-meson decays at Belle II. All presented analyses use a data sample collected at the $\Upsilon(4S)$ resonance by the Belle II experiment corresponding to an integrated luminosity of $189\,\mathrm{fb}^{-1}$. We report three analyses that probe light-lepton universality: The first measurement of a complete set of five angular asymmetries using $\bar{B}^0 \to D^{*+} \ell^- \bar{\nu}_\ell$ decays, followed by a measurement of the forward-backward asymmetry in untagged $\bar{B}^0 \to D^{*+} \ell^- \bar{\nu}_\ell$ decays, and finally, measurements of the branching-fraction ratios $R(D^{*+}_{e/\mu}) = \mathcal{B}(\bar{B}^0 \to D^{*+} e^- \bar{\nu}_e) / \mathcal{B}(\bar{B}^0 \to D^{*+} \mu^- \bar{\nu}_\mu)$, using the same untagged data set, along with the first measurement of the inclusive light-lepton ratio $R(X_{e/\mu}) = \mathcal{B}(\bar{B} \to X e^- \bar{\nu}_e) / \mathcal{B}(\bar{B} \to X \mu^- \bar{\nu}_\mu)$. Furthermore, we present two tests of heavy-to-light lepton universality. In the first test, we report the measurement of the branching-fraction ratio $R(D^{*}_{\tau/\ell})$ using hadronic tagging. In the second test, we present the first measurement of the inclusive ratio $R(X_{\tau/\ell})$. All presented results are consistent with their corresponding Standard Model predictions and, where applicable, with the experimental world averages.
000004045 8560_ $$fjunkerkalefeld@physik.uni-bonn.de
000004045 8564_ $$uhttps://docs.belle2.org/record/4045/files/BELLE2-CONF-PROC-2023-049.pdf