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Loop-level corrections to the neutrino mass

  1. Apr 16, 2012 #1
    Hi,

    Quick question. In the SM, why can't we have loop-level interactions that give neutrinos their small masses?
    (It seems like we must also have Majorana neutrinos)


    Thanks.
     
    Last edited: Apr 16, 2012
  2. jcsd
  3. Apr 16, 2012 #2
    Giving neutrinos a Dirac mass requires there to be right-handed neutrinos and giving them Majorana masses requires a source of explicit lepton number violation. The standard model has neither of these*; so, it can't generate any sort of neutrino masses.

    *Well, strictly, the SM does have non-perturbative lepton number violation; but, only with a compensating violation of baryon number that leaves B-L conserved. Majorana mass requires that this be broken as well.
     
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