I Neutrino Oscillations and Mass

[Trixie Mattel]

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]

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.

 

[Vanadium 50]

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.

 

[mfb]

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.

 

[Orodruin]

It is perfectly fine to have one massless neutrino. It occurs in some (admittedly odd) models, eg, type I seesaw with only two righthanded neutrinos.

 

[Drakkith]

A number of problematic and/or off topic posts and responses have been deleted. Thread re-opened.