Neutrino Oscillations and Mass

Hello

Just wondering, would neutrino oscillations occur is the three standard model neutrinos were the same mass?

or are different masses needed in order to have different phases differences, as the phases differences are why the oscillations occur?

Also why do neutrino oscillations prove that neutrinos are not massless. Is it because the weak eigenstates are a linear superposition of mass eigenstates?

Thank you

mfb
Mentor
Just wondering, would neutrino oscillations occur is the three standard model neutrinos were the same mass?
If all three mass eigenstates have the same mass, there are no oscillations. The oscillation parameters depend on the differences between the squared masses. You have to have non-zero differences for oscillations.

One mass eigenstate could be massless, but that would be odd - it is expected that all three mass eigenstates have a non-zero mass, but currently we are sure only for two of them.

Trixie Mattel
Staff Emeritus
One mass eigenstate could be massless

Can it? I think the standard derivation assumes that all three mass eigenstates have rest frames. There may be some other way to approach it without this assumption.

Trixie Mattel
mfb
Mentor
As far as I know it is no problem to have one mass at exactly zero instead of a very small mass. @Orodruin knows it for sure.

Trixie Mattel
Orodruin
Staff Emeritus