A four-loop Radiative Seesaw Model
  We propose a new type of radiative neutrino model with global hidden $U(1)$ symmetry, in which neutrino masses are induced at the four loop level. Then we discuss the muon anomalous magnetic moment to solve the discrepancy between observation and the standard model prediction, and estimate the relic density of a fermion or boson DM candidate in the model. We also discuss the diphoton resonance $R$ by considering a process $pp \to R \to \gamma \gamma$ as a possible signal of our model. 
Takaaki Nomura, Hiroshi Okada
hep-ph