Quark masses, CKM angles and Lepton Flavour Universality violation

Abstract

A properly defined and suitably broken U(2) flavour symmetry leads to successful quantitative relations between quark mass ratios and CKM angles. At the same time the intrinsic distinction introduced by U(2) between the third and the first two families of quarks and leptons may support anomalies in charged and neutral current semi-leptonic B-decays of the kind tentatively observed in current flavour experiments. We show how this is possible by the exchange of the (3, 1)2/3 vector leptoquark in two U(2)-models with significantly different values of Lepton Flavour Universality violation, observable in foreseen experiments.