A model for the Singlet-Triplet Leptoquarks

Abstract

The deviations of $B$-meson decays measured in $R_{D^{(\ast )}}^{\tau \ell }$ and $R_{K^{(\ast )}}^{\mu e}$ can be explained by the presence of two scalar leptoquarks, a singlet $S_1$ and a triplet $S_3$, mostly coupled to the third generation. We consider a theory of resonances, as an effective description of a strongly interacting theory, that generates the leptoquarks and the Higgs as Nambu-Goldstone bosons, with the rest of the resonances at a scale of order $10-30\mathrm{TeV}$. We assume anarchic partial compositeness for the flavor of the SM fermions. Under these hypothesis we study whether it is possible to reproduce the deviations in the $B$-decays without being in conflict with flavor and electroweak bounds. We find a tension between $R_{D^{(\ast )}}^{\tau \ell }$ and some flavor observables, dominated by flavor violating $\tau$ decays and $\Delta m_{B_s}$, that require a tuning of order $10-25\%$. We also compute the potential of the scalars showing that leptoquarks with masses $O(2-3)\mathrm{TeV}$ can be naturally expected in the model. We discuss briefly the phenomenology of the other resonances.

Comments: 45 pages, 6 figures. All comments welcome