Speaker
Description
Inclusive semileptonic decays of $B$ mesons play a central role in flavour physics, as they provide stringent tests of the Standard Model. These processes can now be studied from first principles using lattice QCD simulations combined with spectral reconstruction techniques. In this talk, we present the first non-perturbative calculation at physical point of the decay rate for the inclusive process $\bar B_s\to X_{\bar sc}\ell\bar\nu$. The calculation is performed using state-of-the-art ETMC gauge ensembles and includes a continuum extrapolation based on three lattice spacings. We employ the Hansen-Lupo-Tantalo method to extract the decay rate directly from Euclidean correlation functions with controlled uncertainties. This study enables the first determination of $|V_{cb}|$ from inclusive semileptonic decays using lattice QCD. By combining our result with the corresponding Belle experimental measurement, we obtain $|V_{cb}|$ with an overall precision of about 8\%, representing a significant step toward resolving the long-standing $|V_{cb}|$ puzzle. The present precision is expected to improve significantly with the inclusion of a fourth lattice spacing and increased statistics, both of which are currently underway.