Testable two-loop radiative neutrino mass model based on an $LLQ{d}^{c}Q{d}^c$ effective operator

Abstract

A new two-loop radiative Majorana neutrino mass model is constructed from the gauge-invariant effective operator $L^i{L}^j{Q}^k{d}^c{Q}^l{d}^c{ϵ}_{ik}{ϵ}_{jl}$ that violates lepton number conservation by two units. The ultraviolet completion features two scalar leptoquark flavors and a color-octet Majorana fermion. We show that there exists a region of parameter space where the neutrino oscillation data can be fitted while simultaneously meeting flavor-violation and collider bounds. The model is testable through lepton flavor-violating processes such as $\mu \to e\gamma$, $\mu \to eee$, and $\mu N\to eN$ conversion, as well as collider searches for the scalar leptoquarks and color-octet fermion. We computed and compiled a list of necessary Passarino-Veltman integrals up to boxes in the approximation of vanishing external momenta and made them available as a Mathematica package, denoted as ANT.

Comments: 42 pages, 11 figures, typo in Eq. (4.9) as well as wrong chirality structures in Secs. 4.5 and 5.2 corrected, final results unchanged