Unraveling the Scotogenic model at muon collider

Abstract

Abstract The Scotogenic model extends the standard model with three singlet fermion Ni and one inert doublet scalar η to address the common origin of tiny neutrino mass and dark matter. For fermion dark matter N1, a hierarchical Yukawa structure $$ \mid {y}_{1e}\mid \ll \mid {y}_{1\mu}\mid \sim \mid {y}_{1\tau}\mid \sim \mathcal{O}(1) $$ ∣ y 1 e ∣ ≪ ∣ y 1 μ ∣ ∼ ∣ y 1 τ ∣ ∼ O 1 is usually favored to satisfy constraints from lepton flavor violation and relic density. Such large μ-related Yukawa coupling would greatly enhance the pair production of charged scalar η± at the muon collider. In this paper, we investigate the dilepton and mono-photon signature of the Scotogenic model at a 14 TeV muon collider. For the dimuon signature "Image missing", we find that most viable samples can be probed with 200 fb−1 data. The ditau signature "Image missing" is usually less promising, but it is important to probe the small |y1μ| region. The mono-photon signature "Image missing" could also probe the compressed mass region M1 ≲ $$ {M}_{\eta^{\pm }} $$ M η ± . Masses of charged scalar η± and dark matter N1 can be further extracted by a binned likelihood fit of the dilepton energy.