First Measurement of $R(X_{\tau /\ell })$ as an Inclusive Test of the $b\to c\tau \nu$ Anomaly

Belle II Collaboration, I. Adachi, K. Adamczyk +390

We measure the tau-to-light-lepton ratio of inclusive $B$-meson branching fractions $R(X_{\tau /\ell })\equiv \mathcal{B}(B\to X\tau \nu )/\mathcal{B}(B\to X\ell \nu )$, where $\ell$ indicate…