Implications of the Jhf-kamioka Neutrino Oscillation Experiment

gives rise to non-trivial effects including oscillations. In this equation, α = e, μ, τ and νi is the state of definite mass mi. The complex numbers Uαi constitute the mixing matrix. Additional light neutral fermions usually known as “sterile neutrinos νs” may also exist. If so, then Eq. (1) must be generalised in the obvious way. For the three flavour case, the mixing matrix can be parameterised in terms of three physical mixing angles and some CP violating phases (the precise number of which depends on whether the neutrino masses are of Dirac or Majorana form). If light sterile neutrinos exist, then there are additional mass and mixing parameters. Oscillations arise due to relative phases between the νi induced by time evolution. Considering two flavours only for simplicity, the mixing pattern