Pati-Salam explanations of the B-meson anomalies

Abstract

We provide a combined explanation of the increasingly tantalizing $B$-meson anomalies, both in $R_{K^{(*)}}$ and $R_{D^{(*)}}$, in the Pati-Salam model with minimal matter content. This well-known model, based on the gauge group $SU(4)_{LC} \times SU(2)_L \times SU(2)_R$, naturally contains a variety of scalar leptoquarks with related and restricted couplings. In particular we show that the seesaw-motivated scalar leptoquark within the representation $(\overline{10}, 3, 1)$ and its right-handed parity partner $(\overline{10}, 1, 3)$ can solve both anomalies while making testable predictions for related observables such as $B \to K\nu\nu$ and $B \to K \mu\tau$. The solution of the $R_{K^{(*)}}$ anomaly alone can be related to a type-II seesaw neutrino mass structure. Explaining also $R_{D^{(*)}}$ requires the existence of a light right-handed neutrino, which constrains the UV structure of the model.