Flavour changing charged current decays at LHCb

The Standard Model (SM) predicts the universality of lepton couplings with the electroweak gauge bosons. Semileptonic decays of $b$-hadrons provide a powerful framework for testing the SM and probing possible New Physics effects. In particular, the processes mediated by charged-current interactions benefit from a relatively large branching fractions and theoretically well-controlled hadronic matrix elements. This contribution presents three recent results from the LHCb experiment: the first measurement of the ratio of branching fractions $\mathcal{R}(D^{\ast \ast })$ using $B^{-}\to D^{\ast \ast 0}{\tau }^{-}{\bar{\nu }}_{\tau }$ decays, the determination of the branching fraction for $\mathrm{\Lambda }\to p{\mu }^{-}{\bar{\nu }}_{\mu }$ and the extraction of form-factor parameters from $B^0\to D^{\ast -}{\mu }^{+}{\nu }_{\mu }$ decays.