One Leptoquark to Rule Them All: A Minimal Explanation for $R_{D^{(\ast )}}$, $R_K$ and $(g-2{)}_{\hat{I}}¼$

Abstract

We show that by adding a single new scalar particle to the Standard Model, a TeV-scale leptoquark with the quantum numbers of a right-handed down quark, one can explain in a natural way three of the most striking anomalies of particle physics: the violation of lepton universality in $\bar{B}\to \bar{K}{\ell }^{+}{\ell }^{-}$ decays, the enhanced $\bar{B}\to D^{(\ast )}\ddot{I}„\bar{\hat{I}}½$ decay rates, and the anomalous magnetic moment of the muon. Constraints from other precision measurements in the flavor sector can be satisfied without fine-tuning. Our model predicts enhanced $\bar{B}\to {\bar{K}}^{(\ast )}\hat{I}½\bar{\hat{I}}½$ decay rates and a new-physics contribution to $B_s-{\bar{B}}_s$ mixing close to the current central fit value.

6 pages, 4 figures; v2: discussion of b->sγ and a new figure added; version accepted by Physical Review Letters