Symmetry and Neutrinos
نویسنده
چکیده
I recount briefly the history of neutrino tribimaximal mixing and the use of the discrete family symmetry A4 in obtaining it. Talk at the 4th International Conference on Flavor Physics, Beijing, September 2007. 1 Neutrino Tribimaximal Mixing In 1978, soon after the putative discovery of the third family of leptons and quarks, it was conjectured by Cabibbo [1] and Wolfenstein [2] independently that U lν = 1 √ 3 1 1 1 1 ω ω 1 ω ω , (1) where ω = exp(2πi/3) = −1/2 + i √ 3/2. This should dispel the myth that everybody expected small mixing angles in the lepton sector as in the quark sector. In 2002, after much neutrino oscillation data have been established, Harrison, Perkins, and Scott [3] proposed the tribimaximal mixing matrix, i.e. U lν =
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