Bimaximal mixing

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Bimaximal mixing is an early idea about how neutrino flavors mix. In this scheme, the third mass state ν3 is an equal mix of muon and tau neutrinos and does not mix with the electron neutrino. The electron neutrino is an equal mix of the first two mass states, ν1 and ν2. The pattern shows a symmetry between the muon and tau flavors and between ν1 and ν2, and it predicts no CP violation. The standard angles are θ12 = 45°, θ23 = 45°, and θ13 = 0 (some conventions use a minus sign for the 45° angles, but θ13 remains zero). This approach, along with tribimaximal and golden-ratio mixing, is part of a class of simple, symmetric mixing schemes. It has been ruled out by experiments that have found a nonzero θ13.