One colorful resolution to the neutrino mass generation, three lepton flavor universality anomalies, and the Cabibbo angle anomaly

Abstract

We propose a simple model to simultaneously explain four observed flavor anomalies while generating the neutrino mass at the one-loop level. Specifically, we address the measured anomalous magnetic dipole moments of the muon, $\Delta a_{\mu }$ , and electron, $\Delta a_e$, the observed anomaly of $b\to s{l}^{+}{l}^{-}$ in the $B$-meson decays, and the Cabibbo-angle anomaly. The model consists of four colorful new degrees of freedom: three scalar leptoquarks with the Standard Model quantum numbers $(3,3,-1/3),(3,2,1/6)$, and $(3,1,2/3)$, and one pair of down-quark-like vector fermion in $(3,1,-1/3)$. The baryon number is assumed to be conserved for simplicity. Phenomenologically viable solutions with the minimal number of real parameters can be found to accommodate all the above-mentioned anomalies and produce the approximate, close to $1\sigma$, neutrino oscillation pattern at the same time. From general consideration, the model robustly predicts: (1) neutrino mass is of the normal hierarchy type, and (2) ${\mathcal{M}}_{ee}^{\nu }\lesssim 3\times 10^{-4}\text{mbox}eV$. The possible UV origin to explain the flavor pattern of the found viable parameter space is briefly discussed. The parameter space can be well reproduced within a simple split fermion toy model.

Comments: 49 pages, 8 figures. v2: Refs added, numerics updated to include new (g-2)_e and global fit. Conclusions unchanged