Flavour non-universal Pati-Salam unification and neutrino masses

The B anomalies, by their distinctive flavour structure i.e. U(2)(5), bring a new piece to the long-standing flavour puzzle. The three-site flavour nonuniversal Pati-Salam (PS) model, which unifies quarks and leptons, provides through the ratios of vacuum expectation values (VEV) acquired at different scales, a combined explanation of the charged and neutral current B anomalies as well as of the mass hierarchies of the Standard Model (SM). The mixings, in new, flavour non-universal, gauge interactions, as well as in the Yukawa couplings, are obtained through suppressed nearest-neighbour interactions. In this three-site model context, the inverse seesaw mechanism is realised, with the minimal addition of three fermion singlets S-L((i)) and where U(1)(F) fermion number is broken dynamically via new singlet scalars Phi(i), yielding an anarchic light neutrino mass matrix in consistency with data, despite the U(2)(5) flavour symmetry observed in the Yukawa matrices. A prediction of this model is Pontecorvo-Maki-Nakagawa-Sakata (PMNS) unitarity violation with a 33 entry close to experimental bounds. The full model finds a natural 5D interpretation with three (almost equidistant) defects in a warped extra dimension, where the exponential hierarchies in VEV ratios of the 413 Lagrangian arise from O(1) differences in the 5D field bulk masses.

Automated summary

The study explores B anomalies with a unique flavour structure and proposes a model that explains the mass hierarchies of the Standard Model using ratios of vacuum expectation values acquired at different scales. The model realizes the inverse seesaw mechanism and predicts PMNS unitarity violation, with a 5D interpretation featuring equidistant defects in a warped extra dimension.