# What is difference between the different 'flavours' of neutrinos?

Moreover, how-come scientist know that muon-neutrino are different from electron-neutrino when they didn't even know what the difference was? Did they interact differently with other particles?

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Firstly, the mass of electron neutrino is different than muon neutrino. The mass of electron neutrino is less than 2.2 eV and the mass of muon neutrino is less than 170 KeV.

From the interaction side of view, electron neutrino is created along with the lepton "electron". On the other hand,muon neutrino is created with the lepton "muon". Most important part is that any flavors of neutrino is created only with its associated lepton.

eg: $n\rightarrow p^++e^-+\bar{\nu}_e$

Here, you can see that electron anti-neutrino is created with the electron. And you also see that in a reaction, suppose muon neutrino is created with electron.But,it is not possible because the conservation of lepton number then will be violated.

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The mass limits you quote are in some sense out dated. All the non-sterile neutrinos are believe (on cosmological grounds) to have masses not more than about 1 eV. –  dmckee Nov 30 '12 at 16:20
Plus since mass eigenstates are not the same as flavor eigenstates, the flavors of neutrinos don't actually have definite masses anyway. –  David Z Nov 30 '12 at 16:30