Neutrino loops from neutrino mixing
  We show how neutrino mixing leads to a softening of the UV behavior of neutrino loops, and can give rise to anomaly-like, but manifestly UV finite amplitudes. This mechanism may be of special significance for the coupling of dark matter-like particles to the Standard Model, as we illustrate with a one-loop example involving the coupling to $W$-bosons. 
Adam Latosinski, Krzysztof A. Meissner and Hermann Nicolai
hep-ph