Lepton Flavour Universality tests in $b \to c l \nu$ decays at LHCb

The Standard Model predicts that the electroweak couplings to the three charged leptons are identical. However, in the last decade, experimental measurements have suggested that semileptonic processes involving taus could have a slightly enhanced decay rate compared to their muonic counterparts. If confirmed, this would be an unambiguous sign of New Physics, with various scenarios introducing additional interactions that couple preferentially to the third generation. Two recent lepton universality tests performed at LHCb are presented in this proceedings of the first edition of the New Frontiers in Lepton Flavour workshop.