TeV-scale vector leptoquark from Pati-Salam unification with vectorlike families

TL;DR

This paper proposes a model with TeV-scale vector leptoquarks from Pati-Salam unification, which can explain the $b o s\mu\mu$ anomaly while evading flavor constraints through vectorlike families.

Contribution

It introduces a novel Pati-Salam based model with vectorlike families that allows a light vector leptoquark compatible with flavor constraints and explains certain B-meson anomalies.

Findings

Leptoquark mass can be at TeV scale, explaining $b o s\mu\mu$ anomaly.

Flavor constraints are alleviated by vectorlike families.

Future experiments will probe most of the parameter space.

Abstract

In this paper, we show an explicit way to realize a TeV-scale vector leptoquark from the Pati-Salam (PS) unification with extra vectorlike families. The leptoquark mass is constrained to be heavier than PeV-scale by the measurement of a flavor violating kaon decay, $K_L \to \mu e$, in conventional models. This strong constraint can be avoided by introducing vectorlike families consistently with the quark and lepton masses and CKM and PMNS matrices. The other flavor violating processes are also suppressed. In this model, the vector leptoquark can be sufficiently light to explain the recent $b\to s\mu\mu$ anomaly, while the $b\to c\tau\nu$ anomaly is difficult to be explained due to the strong constraints from the $Z^\prime$ boson and vectorlike quark searches at the LHC. When the $b\to s\mu\mu$ anomaly is explained, we show that $\mathcal{O}({0.2})$ % tuning is required in the fermion matrix, the future experiments in $\mu\to e\gamma$ and $\mu$-$e$ conversions will cover the most available parameter space, and sizable neutral meson mixings, induced by the extra Higgs doublets, are unavoidable.