Constraining flavour patterns of scalar leptoquarks in the effective field theory

Abstract

We investigate the viability of extending the Standard Model with $S_1$ and $S_3$ 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 $\tau \to \mu \gamma$, ${\bar{B}}_s\to {\tau }^{\pm }{\mu }^{\mp }$ and $B^{+}\to K^{+}{\tau }^{+}{\mu }^{-}$ decays, whose branching ratios are close to the current experimental limits.

Comments: 45 pages, 2 figures, 4 tables; v2 as published in JHEP