What exactly are anti-neutrinos?

  1. According to the the definition of anti-particles, they are particles with same mass but opposite charge. Neutrinos by definition have no charge. So, how can it have an anti-particle?
  2. jcsd
  3. jedishrfu

    Staff: Mentor

  4. Bill_K

    Bill_K 4,159
    Science Advisor

    This is true, but not a complete definition. There are several different things called "charge", and the antiparticle has the opposite value for each.

    Gluons, for example, although they have zero electric charge, they also carry color charge, and so a gluon and its antiparticle have opposite color charge.

    Likewise there are neutral K-mesons K0 and K0-bar which carry opposite strangeness.
  5. So, can we have something like anti-neutron?
  6. jedishrfu

    Staff: Mentor

  7. Thanks. I did not google anti-neutrino before posting. :redface:
  8. Sorry, I meant anti-neutron.
  9. Apart from all, there are studies which propose that the neutrino and antineutrino are the same particle... Those studies consider the neutrino as a Majorana particle (and that's something only neutrally charged particles can be)... That search is based in observing neutrinoless double beta decay.... Unfortunately, we haven't been able to verify that nature so far...
  10. Bill_K

    Bill_K 4,159
    Science Advisor

    Last edited: May 6, 2014
  11. Vanadium 50

    Vanadium 50 17,740
    Staff Emeritus
    Science Advisor
    Education Advisor

    Stackexchange is not a valid source.
  12. Why?
  13. jim mcnamara

    jim mcnamara 1,499
    Science Advisor
    Gold Member

    On stackexchange, like here at PF, anyone can post. Stackexchange depends on a different method of controlling posts by people who are expounding personal research or pet theories. They hope someone in the community will correct the off-the-mark post. PF depends on physicists, who try to remove crackpot posts. And there is active correction. Bill K is being polite. "rob" is expounding what appears to be a pet theory. Note that he has about 640 "status points". The point system is supposed to let you in on the believable-ness of the poster in general.
    Last edited: May 6, 2014
  14. Ok. I get what you say. I just mentioned the link because I found a more detailed answer there.
  15. phinds

    phinds 8,757
    Gold Member

    "detailed" does not necessarily have anything to do with "correct". Check your sources. There's a list here at PF for those that are good/bad.
  16. I never said that neutrinos are Majorana particles... What I said is that there is a lot of work being done in studying that theory and confirming it... and as I pointed out, experiments have been fruitless until now (equivalently said, there's not been experimental verification of physics beyond the Standard Model, only indirect signs). If we verify the neutrinoless double beta decay, there will be a problem with the accidental symmetries of Baryon and Lepton numbers (they will be violated) which appears in the Standard Model.
    The big thing is the difficulties in measuring that experimentally (as neutrinos have always been), the rarity of the events (ordinary double beta decay is very slow itself) and of course the clearness of the subject material and "technology" .
  17. Orodruin

    Staff: Mentor

    Neutrino oscillations in themselves are an observation of physics beyond the Standard Model since lepton flavor is conserved in the SM. (Gravity also seems to be a fairly established observation of BSM physics.) Furthermore, B and L are not separate accidental symmetries of the Standard Model but B+L may be violated through non-perturbative effects. Anyway, breaking B-L would be good news for the possibility of generating the baryon asymmetry of the Universe.
  18. mfb

    Staff: Mentor

    I think you mixed + and - here. Many models propose B and L non-conservation, but a conserved B-L (which implies a non-conserved B+L).
  19. I am not sure whether B and L can be violated in the Standard Model... in which case?
    As for the neutrino oscillations, that's not something the SM could not deal with. I guess it should be better called extension of the standard model rather than physics beyond it... PMNS is fine with doing that job.
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