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

A bstract We present Standard Model predictions for lepton flavour universality ratios of inclusive B → X ( c ) ℓ ν ¯ ℓ . 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 (*) ℓ ν ¯ ℓ modes, in which tensions exists between the predictions and measurements in those modes.