Standard Model predictions for Lepton Flavour Universality ratios of inclusive semileptonic $B$ decays

We present Standard Model predictions for lepton flavour universality ratios of inclusive $B\to X_{(c)}\mathrm{\ell }{\bar{\nu }}_{\mathrm{\ell }}$. For the $\mathrm{\ell }=\mu ,e$, these ratios are very close to unity as expected. For the $\tau$ mode, we update the SM prediction for the branching ratio including power-corrections in the heavy-quark expansion up to $1\mathrm{/}{m}_b^3$. These inclusive ratios serve as an important cross-check of the exclusive $B\to D^{(\ast )}\mathrm{\ell }{\bar{\nu }}_{\mathrm{\ell }}$ modes, in which tensions exists between the predictions and measurements in those modes.