A combined explanation of the B-decay anomalies with a single vector leptoquark

International audienceIn order to simultaneously account for both RD(∗) andRK(∗) anomalies in B-decays, we consider an extensionof the Standard Model by a single vector leptoquark field, and studyhow one can achieve the required lepton flavour non-universality,starting from a priori universal gauge couplings. While the unitaryquark-lepton mixing induced by SU(2)L breaking is insufficient,we find that effectively nonunitary mixings hold the key tosimultaneously address the RK(∗) and RD(∗)anomalies. As an intermediate step towards various UV-completemodels, we show that the mixings of charged leptons with additionalvector-like heavy leptons successfully provide a nonunitaryframework to explain RK(∗) and RD(∗).These realisations have a strong impact for electroweakprecision observables and for flavour violating ones: isosingletheavy lepton realisations are already excluded due to excessivecontributions to lepton flavour violating Z-decays.Furthermore, in the near future, the expected progress in the sensitivityof charged lepton flavour violation experiments should allow to fully probethis class of vector leptoquark models