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

In this paper, we show an explicit way to realize a TeV-scale vector leptoquark from the Pati-Salam 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 -> mu e, in conventional models. This strong constraint can be avoided by introducing vectorlike families consistently with the quark and lepton masses and Cabbibo-Kobayashi-Maskawa and Pontecorvo-Maki-Nakagawa-Sakata matrices. In this model, the vector leptoquark can be sufficiently light to explain the recent b -> s mu mu anomaly, while the b -> c tau nu anomaly is difficult to be explained due to the strong constraints from the Z' boson and vectorlike quark searches at the LHC. When the b -> s mu mu anomaly is explained, we show that O (0.2)% tuning is required in the fermion matrix, the future experiments in mu -> e gamma and mu-e conversions will cover most available parameter space, and sizable neutral meson mixings, induced by the extra Higgs doublets, are unavoidable.

Automated summary

The paper presents an explicit method to realize a TeV-scale vector leptoquark from Pati-Salam unification with extra vectorlike families, which can avoid strong constraints in conventional models. The model can explain the b -> s mu mu anomaly, but faces difficulties in explaining the b -> c tau nu anomaly due to constraints from Z' boson and vectorlike quark searches at the LHC.