Bimaximal mixing refers to a proposed form of the lepton mixing matrix. It is characterized by the neutrino being a bimaximal mixture of and and being completely decoupled from the , i.e. a uniform mixture of and . The is consequently a uniform mixture of and . Other notable properties are the symmetries between the and flavours and and mass eigenstates and an absence of CP violation. The moduli squared of the matrix elements have to be:
According to PDG convention, bimaximal mixing corresponds to and , which produces following matrix:
Alternatively, and can be used, which corresponds to:
The L/E flatness of the electron-like event ratio at Super-Kamiokande severely restricts the CP-conserving neutrino mixing matrices to the form:
Bimaximal mixing corresponds to . Tribimaximal mixing and golden-ratio mixing also correspond to an angle in the above parametrization. Bimaximal mixing, along with these other mixing schemes, have been falsified by a non-zero .