PDA

View Full Version : Beyond the electron neutrino


qsefthuko66
Feb11-11, 06:54 AM
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?

mathman
Feb11-11, 03:57 PM
The electron neutrino has the smallest non-zero mass of all known particles.

Parlyne
Feb11-11, 11:04 PM
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.

chrispb
Feb16-11, 10:16 AM
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.

Parlyne
Feb16-11, 11:07 AM
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.

chrispb
Feb16-11, 07:25 PM
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.

rvsupply
Feb16-11, 10:53 PM
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

rvsupply
Feb17-11, 10:43 PM
is it hard to mix them?

rvsupply
Feb17-11, 10:44 PM
any idea of mixing angles to 0 or to make neutrino mass states degenerate i think this easy if you have a great trainer....