Nuetrino Oscillation entanglement

[whynothis]

I have read statements which basically suggest that nuetrino oscillation prohibits any strict statement of conservation of lepton number. Is this true or is it possible that nuetrinos produced along with electrons, muons and taus become entangled so that lepton number is still strictly conserved.

Also, what do theorist say about this. I am under the impression that we have models of nuetrino oscillation. Do they predict strict conservation of lepton number? Can they even address this question?

 

[genneth]

Neutrino oscillations require that they have mass. There are a number of mass generating mechanisms proposed. One of them would make neutrinos their own antiparticles (making them the only fermion to have the property), which would violate lepton number conservation. Many other ways to generate mass would not violate lepton number conservation. Whether we do or not will require experimental input; there are currently many neutrino related experiments being carried out. One of them is trying a fairly direct way to see if the neutrinos are their own antiparticles, which is to observe a neutrino-less double beta decay. Such a process would also directly violate lepton conservation (since it would create two electrons without any anti-leptons). One group has claimed to see it at a statistically significant level; their findings are not widely accepted, and have not be reproduced.

 

[JustinLevy]

It sounds like the two previous posts are using a different meaning for "lepton number". Whynotthis seems to mean lepton 'family' number (without oscillations, it was once thought that the electron lepton number, muon lepton number, and tau lepton number could be individually conserved). Whereas genneth seems to refer to the overall lepton number.

It is my understanding that neutrino oscillation violates the lepton family number. Whynotthis, your proposal for fixing this would require electrons, muons, and taus that are the products of weak decays to also oscillate between the families ... which is not observed.


EDIT: I just checked out the wikipedia article. It comments that in the standard model, even the overall "lepton number conservation law in fact is violated by chiral anomalies". I have never gotten a good grasp on what a chiral anomalie is. So first, is this correct? And second, would someone mind expanding on that statement a bit? Thanks.