Probing the scotogenic FIMP at the LHC
  We analyse the signatures at the Large Hadron Collider (LHC) of the scotogenic model, when the lightest Z2-odd particle is a singlet fermion and a feebly interacting massive particle (FIMP). We further assume that the singlet fermion constitutes the dark matter and that it is produced in the early Universe via the freeze-in mechanism. The small couplings required to reproduce the observed dark matter abundance translate into decay-lengths for the next-to-lightest Z2-odd particle which can be macroscopic, potentially leading to spectacular signatures at the LHC. We characterize the possible signals of the model according to the spectrum of the Z2-odd particles and we derive, for each of the cases, bounds on the parameters of the model from current searches. 
Andre Hessler, Alejandro Ibarra, Emiliano Molinaro and Stefan Vogl
hep-ph