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

TL;DR

This paper proposes a simple, colorful model with new particles to simultaneously explain multiple flavor anomalies, neutrino masses, and predict specific neutrino mass hierarchy and constraints, providing a unified approach to these phenomena.

Contribution

The model introduces three scalar leptoquarks and a vector fermion to address flavor anomalies and neutrino mass generation simultaneously, with minimal parameters and specific predictions.

Findings

Successfully explains muon and electron magnetic moments, B-meson decay anomalies, and the Cabibbo angle anomaly.

Predicts neutrino mass hierarchy as normal and an upper bound on the effective Majorana mass.

Provides a viable parameter space consistent with observed anomalies and neutrino oscillation data.

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 $b\rightarrow s l^+ l^-$ 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) ${\cal M}^\nu_{ee}\lesssim 3\times 10^{-4}\mbox{eV}$. 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.