Radiative type III seesaw model and its collider phenomenology

Abstract

We analyze the present bounds of a scotogenic model, the Radiative Type III Seesaw (RSIII), in which an additional scalar doublet and at least two fermion triplets of SU (2) L are added to the Standard Model (SM). In the RSIII the new physics (NP) sector is odd under an exact global Z 2 symmetry. This symmetry guaranties that the lightest NP neutral particle is stable, providing a natural dark matter (DM) candidate, and leads to naturally suppressed neutrino masses generated by a one-loop realization of an effective Weinberg operator. We focus on the region with the highest sensitivity in present and future LHC searches, with light scalar DM and at least one NP fermion triplet at the sub-TeV scale. This region allows for significant production cross-sections of NP fermion pairs at the LHC. We reinterpret a set of searches for supersymmetric particles at the LHC obtained using the package CheckMATE, to set limits on our model as a function of the masses of the NP particles and their Yukawa interactions. The most sensitive search channel is found to be dileptons plus missing transverse energy. In order to target the case of tau enhanced decays and the case of compressed spectra we reinterpret the recent slepton and chargino search bounds by ATLAS. For a lightest NP fermion triplet with a maximal branching ratio to either electrons or muons we exclude NP fermion masses of up to 650 GeV, while this bound is reduced to approximately 400 GeV in the tau-philic case. Allowing for a general flavor structure we set limits on the Yukawa couplings, which are directly related to the neutrino flavor structure.

Lepton Flavor Violation in the singlet-triplet scotogenic model

“…Regarding collider phenomenology, the Σ and Ω triplets can be pair-produced in Drell-Yan processes at the LHC. In case of the Σ fermions, their subsequent decays lead to final states including DM particles, hence to signatures with missing energy, in a way analogous to the standard R-parity conserving supersimmetric signals [79]. These interesting possibilities are left for future work.…”

The inert Zee model

“…As expected, and in contrast to the selectron and smuon pair production, there is no sensitivity to left-or right-stau pair production. By using the same strategy than in [62], we focus in the excluded cross section plot presented in figure 12 of ref. [61] for a DM particle of 60 GeV, since it is a representative value in the case of the IDM to account for the proper relic density.…”

Doublet-triplet dark matter with neutrino masses

“…For example, if a Z 2 -odd doublet scalar with Y = 1 is added we get the model classified as the T-3-C model with α = −1 in Ref. [32], which allows one-loop neutrino masses through the topology T-3 [31], as in the radiative type III seesaw model [33][34][35]. If instead we add a real triplet scalar, we arrive at a similar conclusion, this time with the model T1-3-H and α = 0 of Ref.…”