We show a general form of neutrino mass matrix (M), whose matrix elements are denoted by M_{ ij} (i.j=e, mu, tau) as flavor neutrino masses, that induces maximal CP violation as well as maximal atmospheric neutrino mixing. The masses of M_{ mu mu}, M_{ tau tau} and M_{ mu tau}+sigma M_{ ee} (sigma =\pm 1) turn out to be completely determined by M_{ e mu} and M_{ e tau} for given mixing angles. The appearance of CP violation is found to originate from the interference between the mu-tau symmetric part of M and its breaking part. If |M_{ e mu}|=|M_{ e tau}|, giving either M_{ e mu}=-sigma e^{ i theta} M_{ e tau} or M_{ e mu}=-sigma e^{ i theta}M*_{ e tau} with a phase parameter theta, is further imposed, we find that |M_{ mu mu}|=|M_{ tau tau}|is also satisfied. These two constraints can be regarded as an extended version of the constraints in the mu-tau symmetric texture given by M_{ e mu}=-sigma M_{ e tau} and M_{ mu mu}=M_{ tau tau}. Majorana CP violation becomes active if arg(M_{ mu tau})\neq arg(M_{ e mu})+theta/2 for M_{ e mu}=-sigma e^{ i theta} M_{ e tau} and if arg(M_{ mu tau})\neq theta/2 for M_{ e mu}=-sigma e^{ i theta} M*_{ e tau}.
Categories: hep-ph