Standard Model predictions for lepton flavour universality ratios of inclusive semileptonic B decays

Abstract

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