Testing radiative neutrino mass models at the LHC

Abstract

The Large Hadron Collider provides us new opportunities to search for the origin of neutrino mass. Beyond the minimal see-saw models a plethora of models exist which realise neutrino mass at tree- or loop-level, and it is important to be sure that these possibilities are satisfactorily covered by searches. The purpose of this paper is to advance a systematic approach to this problem. Majorana neutrino mass models can be organised by SM-gauge-invariant operators which violate lepton number by two units. In this paper we write down the minimal ultraviolet completions for all of the mass-dimension 7 operators. We predict vector-like quarks, vector-like leptons, scalar leptoquarks, a charged scalar, a scalar doublet, and a scalar quadruplet, whose properties are constrained by neutrino oscillation data. A detailed collider study is presented for $$ {\mathcal{O}}_3=LLQ\overline{d}H $$ and $$ {\mathcal{O}}_8=L\overline{d}{\overline{e}}^{\dagger }{\overline{u}}^{\dagger }H $$ completions with a vector-like quark $$ \chi \sim \left(3,2,-\frac{5}{6}\right) $$ and a leptoquark $$ \phi \sim \left(\overline{3},1,\frac{1}{3}\right) $$ . The existing LHC limits extracted from searches for vector-like fermions and sbottoms/stops are m χ ≳ 620 GeV and m ϕ ≳ 600 GeV.