A Three-Loop Neutrino Model with Global $U(1)$ Symmetry
  We study a three-loop induced neutrino model with a global $U(1)$ symmetry at TeV scale, in which we naturally accommodate a bosonic dark matter candidate. We discuss the allowed regions of masses and quartic couplings for charged scalar bosons as well as the dark matter mass on the analogy of the original Zee-Babu model, and show the difference between them. We also discuss the possibility of the collider searches, in which future like-sign electron liner collider could be promising. 
Hisaki Hatanaka, Kenji Nishiwaki, Hiroshi Okada and Yuta Orikasa
hep-ph