Fusion of two neutrinos

What are the results of fusing an electron neutrino and a muon neutrino? If you have an answer, then why? I looked this up and searched for stuff on Google, Wikipedia and a few other sites, but all the results say are stuff on nuclear fusion and neutrinos.

BONUS QUESTION:
What happens if you put another muon neutrino into the mix?

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But then free-propagating neutrinos are not in pure flavor states except by chance anyway, so any pair of neutrino and anti-neutrino1 could participate in a vertex $$\nu_l + \bar\nu_l \to Z^0 \,,$$ which is roughly equivalent to Drell-Yan in the charged lepton sector with a projection into agreeing flavor states ($l$) built into the operator.
The cross-section will be very low and the $Z$ will have to decay to something on-shell very quickly so there are energy and momentum conservation requirements.