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Neutrino oscilation-theoretical reason

  1. Aug 24, 2011 #1
    Is it possible shortly to explain, what is reason that neutrinos oscilate, from one color to others?
    It can be found some articles, but, is it possible in a few word, maybe in similar language as Feynman, who use basic rules of quantum physics.
  2. jcsd
  3. Aug 25, 2011 #2


    Neutrino oscillation arises from a mixture between the flavor and mass eigenstates of neutrinos. That is, the three neutrino states that interact with the charged leptons in weak interactions are each a different superposition of the three neutrino states of definite mass. Neutrinos are created in weak decays and reactions in their flavor eigenstates[nb 1]. As a neutrino propagates through space, the quantum mechanical phases of the three mass states advance at slightly different rates due to the slight differences in the neutrino masses. This results in a changing mixture of mass states as the neutrino travels, but a different mixture of mass states corresponds to a different mixture of flavor states. So a neutrino born as, say, an electron neutrino will be some mixture of electron, mu, and tau neutrino after traveling some distance. Since the quantum mechanical phase advances in a periodic fashion, after some distance the state will nearly return to the original mixture, and the neutrino will be again mostly electron neutrino. The electron flavor content of the neutrino will then continue to oscillate as long as the quantum mechanical state maintains coherence. It is because the mass differences between the neutrinos are small that the coherence length for neutrino oscillation is so long, making this microscopic quantum effect observable over macroscopic distances.

    So can the above be boiled down into one sentence?
  4. Aug 25, 2011 #3
    If neutrinos can be produced in an eigenstate of flavor via the weak interaction can they also be produced in an eigenstate of mass?

    Do electrons oscillate like neutrinos?
    Last edited: Aug 25, 2011
  5. Aug 25, 2011 #4


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    Good question.

    For quarks there is a similar mixing, the so-called CKM-matrix. I see no reason why there shouldn't be something similar for the electron (which would mix with the muon and the tau)
  6. Aug 25, 2011 #5


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    I think an essential ingredient in neutrino mixing is the extremely small mass difference. The only other similar case being the K-long/K-short system. In order to observe mixing, in the reaction in which the particles are produced the two outcomes (e, νe) and (μ, νμ) would need to be coherent, and with the large mass difference between electron and muon this won't happen.
  7. Aug 25, 2011 #6
  8. Aug 25, 2011 #7
    Neutrino mixing is precisely this "something similar". Recall that for quark mixing, we have the choice of mixing either the up-type quarks or the down-type quarks (or both with some redundancy). On the leptonic side, we have the choice of mixing either the neutrinos or the charged leptons (or both with some redundancy).

    Bill_K's remark about the extremely small neutrino mass differences is the usual justification for mixing the neutrinos rather than the charged leptons: neutrino oscillations are far more likely than charged lepton oscillations. But the math works out either way.

  9. Aug 27, 2011 #8
    I went through. It write mostly how to calculate oscillations, if we have 2 or more mass states.
    1. I do not understand, why every arising of neutrinost (sun, for instance) give 3 mass states, why not only one state.

    2. I do not understand why we have not only K0 state, why we have K0 and Kbar0 state.

    3. I assume that electron also transfers to muon and back, as you wrote above?

    4. So very strange transfers are possible electron to proton? or not because of conservation of lepton number?
    Is this question of particle physics, not of quantum mechanics.

    5. Is change of one color neutrino to another, or change of K0 to Kbar0 effect of quantum mechanics or particle effect?
    Last edited: Aug 27, 2011
  10. Aug 27, 2011 #9
    That was your first question and a good one! The same paper you went through gave a great example about light on page 20:


    In the paper we learn light can be described by two different basis, linear verses circular polarization. Linear polarized light can be though of as equal parts left and right circularly polarized light with proper phase difference? In the Faraday Effect the different left and right polarized light propagate at different velocities so the relative phase changes and so rotates the plane of linear polarized light.

    The neutrino mass states can be thought of as the circularly polarized light and the flavor states can be thought of as the linear polarized light.

    So we have things that can be described in different basis and depending on how these things are produced we chose the proper basis to make life easier?

    So thinking of a neutrino think of a three sided tapered cylinder that changes side area with time that that we get to flip in the air, catch, and call its flavor (a tapered cylinder could give three different probables that added up to one and if the cylinder changed shape the probabilities could change)?

    I know, cylinders have nothing to do with neutrinos. %^)
    Last edited: Aug 27, 2011
  11. Aug 27, 2011 #10
    No. While muons and tau leptons are essentially "electrons, only heavier", the proton is a completely different beastie. Among other things, the proton is a composite object formed of quarks and gluons, whereas all the leptons are elementary point particles to the limit of our current experimental resolution.

    For more information, see
  12. Aug 28, 2011 #11
    Thus, electron neutrino is built up from three masses and so it changes flavor.
    Why then electron does not change flavor to muon. Is so short or so long wavelenght?
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