Significant deviations from the standard model are observed in semileptonic charged and neutral-current $B$ decays, the muon magnetic moment, and the extraction of the Cabibbo angle. We propose that these deviations point towards a coherent pattern of new physics effects induced by two scalar mediators, a leptoquark $S_1$ and a charged singlet ${\varphi }^{+}$. While $S_1$ can provide solutions to charged-current $B$ decays and the muon magnetic moment, and ${\varphi }^{+}$ can accommodate the Cabibbo-angle anomaly independently, their one-loop level synergy can also address neutral-current $B$ decays. This framework provides the most minimal explanation to the above-mentioned anomalies, while being consistent with all other phenomenological constraints.

• Received 23 April 2021
• Accepted 22 June 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.061803

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Published by the American Physical Society