Dirac neutrinos with S4S4 flavor symmetry in warped extra dimensions

We present a warped extra dimension model with the custodial symmetry SU(2)L×SU(2)R×U(1)X×PLRSU(2)L×SU(2)R×U(1)X×PLR based on the flavor symmetry S4×Z2×Z2′, and the neutrinos are taken to be Dirac particles. At leading order, the democratic lepton mixing is derived exactly, and the high-dimensional operators introduce corrections of order λcλc to all the three lepton mixing angles such that agreement with the experimental data can be achieved. The neutrino mass spectrum is predicted to be of the inverted hierarchy and the second octant of θ23θ23 is preferred. We suggest the modified democratic mixing, which is obtained by permuting the second and the third rows of the democratic mixing matrix, should be a good first order approximation to understanding sizable θ13θ13 and the first octant of θ23θ23. The constraints on the model from the electroweak precision measurements are discussed. Furthermore, we investigate the lepton mixing patterns for all the possible residual symmetries GνGν and GlGl in the neutrino and charged lepton sectors, respectively.