Proof that neutrino flavor oscillation implies nonzero neutrino mass?

In summary, the conversation discusses the search for better references regarding the proof that nonzero neutrino masses imply neutrino flavor oscillation. It is mentioned that usually, a good starting point is the PDG and to follow the references they provide. It is also stated that the fact that we observe neutrino oscillation implies that neutrino masses must be non-degenerate. However, the connection between neutrino mass and oscillation is not straightforward and can vary depending on the specific neutrino mass model.
  • #1
strangerep
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[This is a reference request.]

I'm dissatisfied with the "proofs" I've found so far. E.g., in Kayser's review from 2008, in the paragraph following his eq(1.4), he assumes a propagation amplitude Prop##(\nu_i)## of ##\exp(-im_i \tau_i)##, where "##m_i## is the mass of the ##\nu_i## and ##\tau_i## is the proper time that elapses in the ##\nu_i## rest frame during its propagation". I.e., he assumes ##m_i \ne 0##. Thus, he proves only that nonzero neutrino masses imply neutrino flavor oscillation, but not the converse, afaict.

Can anyone point me to better references, pls?
 
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  • #2
As far as I know, neutrino oscillation only depends on ##\Delta m^2##, i.e. the difference of the square of masses, so the fact that we observe ##\nu_e - \nu_\mu## and ##\nu_e - \nu_\tau## oscillation tells us that the masses of the neutrinos must be non-degenerate (and therefore at most only one can be 0).
I don't know what are good references, although neutrino oscillation is covered in a lot of books.
Usually, a good idea is to start with PDG and follow the references they give.
 
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  • #3
strangerep said:
[This is a reference request.]

I'm dissatisfied with the "proofs" I've found so far. E.g., in Kayser's review from 2008, in the paragraph following his eq(1.4), he assumes a propagation amplitude Prop##(\nu_i)## of ##\exp(-im_i \tau_i)##, where "##m_i## is the mass of the ##\nu_i## and ##\tau_i## is the proper time that elapses in the ##\nu_i## rest frame during its propagation". I.e., he assumes ##m_i \ne 0##. Thus, he proves only that nonzero neutrino masses imply neutrino flavor oscillation, but not the converse, afaict.

Can anyone point me to better references, pls?
Isn't this the way physics usually proceeds? Let ##T## be a particular theory, and ##E## be a particular experiment result. Now suppose that it can be show that ##T \Rightarrow E##. If an actual experiment is performed and ##E## is the result, we take this as evidence for, but not proof of, ##T##.

Theories involving massive neutrinos predict oscillations, which predict experiment results ##E_i##. Actual experiments produce some of these ##E_i##, which we take as evidence that (at least some) neutrinos have mass.
 
  • #4
Since oscillations only require mass difference, how does "neutrinos having mass", by implication all of them, lead to oscillations, or vice versa? If some neutrinos have nonzero mass and other/s zero, would oscillations still result? And vice versa, if neutrinos had masses but these were equal, it would still have no oscillations.
 
  • #5
snorkack said:
Since oscillations only require mass difference, how does "neutrinos having mass", by implication all of them, lead to oscillations, or vice versa? If some neutrinos have nonzero mass and other/s zero, would oscillations still result? And vice versa, if neutrinos had masses but these were equal, it would still have no oscillations.
It does not. It is a somewhat simplified statement. The conclusion is that there is flavor mixing in the lepton sector and that neutrinos have different masses. From that follows that at most one neutrino is massless. You can argue about how natural it would be to have a single massless neutrino when the others have non-zero masses, but there are indeed neutrino mass models where this could happen.
 
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  • #6
If the masses are all the same (e.g. 0) then the flavor eigenstates (and every other state) are also mass eigenstates and no mixing happens. This is analogous to e.g. neutral meson mixing where we use the observed mixing to determine that there is a mass difference.
 
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1. What is neutrino flavor oscillation?

Neutrino flavor oscillation is the phenomenon where a neutrino changes from one flavor to another as it travels through space. This is possible due to the fact that neutrinos have mass, which allows them to interact with each other and change flavors.

2. How does neutrino flavor oscillation imply nonzero neutrino mass?

Neutrino flavor oscillation is only possible if neutrinos have mass. This is because the process of changing flavors requires the neutrino to have different energy levels, which can only occur if they have mass. Therefore, the observation of neutrino flavor oscillation is strong evidence for the existence of nonzero neutrino mass.

3. What is the evidence for neutrino flavor oscillation?

The evidence for neutrino flavor oscillation comes from various experiments, including the Super-Kamiokande and Sudbury Neutrino Observatory experiments. These experiments have observed a deficit in the expected number of neutrinos from the sun and from cosmic rays, suggesting that neutrinos are changing flavors as they travel through space.

4. How does this discovery impact our understanding of particle physics?

The discovery of neutrino flavor oscillation has significant implications for our understanding of particle physics. It confirms the existence of neutrino mass, which was previously only theorized. This discovery also challenges the Standard Model of particle physics, as it suggests that there may be new physics beyond what is currently understood.

5. What are the potential applications of this discovery?

The discovery of neutrino flavor oscillation has potential applications in various fields, including astrophysics and cosmology. It can help us better understand the behavior of neutrinos in extreme environments, such as supernovae and black holes. It can also provide insights into the evolution of the universe and the role of neutrinos in shaping it.

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