Lepton mixing from the interplay of the alternating group A5 and CP

Abstract: Assuming three generations of Majorana neutrinos, we study the different mixing patterns that arise from the non-trivial breaking of the flavor group A5 and CP to the residual symmetries Z3, Z5 or Z2 × Z2 in the charged lepton and to Z2 × CP in the neutrino sector. All patterns contain only one free parameter θ and thus mixing angles as well as the Dirac and the two Majorana phases are strongly correlated. We perform an analytical and a numerical study of all possible mixing patterns. It turns out that only four patterns can describe the experimentally measured values of the mixing angles for a particular choice of θ well. All of them predict trivial Majorana phases, while the Dirac phase δ is maximal for two patterns and trivial for the two remaining ones. If δ is maximal, also the atmospheric mixing angle is fixed to be maximal.