# Beyond the electron neutrino

## Main Question or Discussion Point

Do you know a particle smaller than an electron neutrino? An electron neutrino is far by the smallest particle I know! Do you know something smaller than that?

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mathman
The electron neutrino has the smallest non-zero mass of all known particles.

The electron neutrino has the smallest non-zero mass of all known particles.
The electron neutrino doesn't have a well-defined mass. It's a superposition of the three neutrino mass eigenstates, the lightest of which is the lightest know fermion. However, it is not know whether the lightest neutrino has a non-zero mass.

The electron neutrino doesn't have a well-defined mass. It's a superposition of the three neutrino mass eigenstates, the lightest of which is the lightest know fermion. However, it is not know whether the lightest neutrino has a non-zero mass.
If the lightest neutrino had zero mass, then the determinant of the mass matrix would be 0 and neutrino oscillations would not occur.

If the lightest neutrino had zero mass, then the determinant of the mass matrix would be 0 and neutrino oscillations would not occur.
You are correct that the determinant would be 0; however, I believe that you are incorrect that that would eliminate oscillations. As far as I know, the only ways to prevent oscillations are to set mixing angles to 0 or to make neutrino mass states degenerate. Neither of these possibilities are guaranteed by a 0 determinant.

You are correct that the determinant would be 0; however, I believe that you are incorrect that that would eliminate oscillations. As far as I know, the only ways to prevent oscillations are to set mixing angles to 0 or to make neutrino mass states degenerate. Neither of these possibilities are guaranteed by a 0 determinant.
Ah, yes, it's not m^2 that factors into the calculation, but delta m^2. My mistake.

oh! really is it true the only ways to prevent oscillations are to set mixing angles to 0 or to make neutrino mass states degenerate

is it hard to mix them?

any idea of mixing angles to 0 or to make neutrino mass states degenerate i think this easy if you have a great trainer....