Due to the surplus of electron neutrino led people to suggest the possibility of 4th neutrino flavour, and it is thought to only interact with gravity and nothing else not even weak interaction. So is anti sterile neutrino possible and how can we distinguish them apart? So when muon neutrino and muon anti-neutrino both oscillate into their respective sterile neutrino and sterile anti-neutrino, do they annihilate each other on contact?

Note: I know sterile neutrino is a hypothetical particle so I'm looking for theoretical solution since people have starting to modify the standard model to make some space for them.

  • $\begingroup$ You want to know how the enhanced disappearance of neutrinos into sterile neutrinos differs from the enhanced disappearance of antineutrinos into sterile antineutrinos? Have you read up on the respective PMNS-like mixing matrices? $\endgroup$ Jan 8, 2019 at 3:25
  • $\begingroup$ @CosmasZachos: I just googled it and I hope you can provide some links on PMNS-like mixing matrix especially for intro to intermediate level, thanks. $\endgroup$
    – user6760
    Jan 8, 2019 at 3:41
  • $\begingroup$ Try the links on the right. Or this talk, cgc.physics.miami.edu/Miami2018/Hewes2018.pdf $\endgroup$ Jan 8, 2019 at 3:51

1 Answer 1


Regular neutrino oscillations are different for neutrinos and anti-neutrinos. This difference is governed by the complex phase called delta, which is one of the poorest measured parameters in particle physics (progress will be coming soon (~10 years) with DUNE and T2HK).

If you want to add in a sterile neutrino, you'd want to extend the lepton mixing matrix to 4x4. Assuming unitarity and all relevant rephasing for oscillations means that you go from three mixing angles and one complex phase to six mixing angles and three complex phases. If the additional complex phases are non-zero then yes, the sterile oscillations could be different for neutrinos and anti-neutrinos.

We can experimentally distinguish them in a number of ways. Most neutrino sources produce either neutrinos or anti-neutrinos. For example, nuclear reactors produce only electron anti-neutrinos. Accelerator sources can be tuned to be either muon neutrinos or muon anti-neutrinos.


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