New type of complex neutrino mass texture and μ-τ symmetry -: art. no. 015002

Relying upon the usefulness of the mu-tau symmetry, we find a new type of neutrino mass texture with a single phase parameter delta that describes maximal atmospheric neutrino mixing and Dirac CP violation due to the presence of delta. The Majorana phase associated with the third massive neutrino turns out to be identical to the Dirac phase while other Majorana phases vanish. The nonvanishing reactor neutrino mixing angle theta(13) is induced by a mu-tau symmetry breaking effect. Flavor neutrino masses that supply the mu-tau symmetry breaking terms become pure imaginary for delta=+/-pi/2, leading to maximal CP violation. There is a parameter denoted by eta, which is either O(Delta m(2)/Delta m(atm)(2)) in the normal mass hierarchy, or O(root Delta m(2)/Delta m(atm)(2)) in the inverted mass hierarchy. In the inverted mass hierarchy, the contribution of O(sin(2)theta(13)) is found to be significant and cannot be neglected. Our texture also leads to quasidegenerate neutrinos with masses of O(root Delta m(atm)(2)), which serves as the scale for the effective neutrino mass in (beta beta)(0 nu) decay. This texture does not include eta, and Delta m(2) naturally arises from contributions of O(sin(2)theta(13)) to give Delta m(2)/Delta m(atm)(2)similar to sin(2)theta(13), yielding the prediction of sin(2)theta(13)=O(10(-2)).