Constraining Flavour Patterns of Scalar Leptoquarks in the Effective Field Theory

We investigate the viability of extending the Standard Model with S1 and S3 scalar leptoquarks when the flavour structure is parametrized in terms of Froggatt-Nielsen charges. In contrast to a similar analysis with a vector leptoquark, we find essentially two solutions for the charges that fit the experimental constraints, which are dominated by the current tensions in B decays. These two scenarios differ in their estimate of the anomalous magnetic moment of the muon, (g − 2), but they both predict sizeable contributions to τ → μγ, $$ {\overline{B}}_s $$ → τ ±μ∓ and B+ → K +τ +μ− decays, whose branching ratios are close to the current experimental limits.