Nonzero θ13 with unbroken μ - τ symmetry of the active neutrino mass matrix in the presence of a light sterile neutrino

We revisit the possibility of generating a nonzero reactor mixing angle in a scenario where there is a sterile neutrino at the eV scale apart from the usual three sub-eV scale active neutrinos. We show that the 3 x 3 active neutrino mass matrix can possess a mu - tau symmetry and can still be consistent with the nonzero value of the reactor mixing angle theta(13) if this mu - tau symmetry is broken in the sterile neutrino sector. We first propose a simple model based on the discrete flavor symmetry A(4) x Z(3) x Z(3)(') to realize such a scenario and then numerically evaluate the complete 3 + 1 neutrino parameter space that allows such a possibility. We show that the possibility of generating a nonzero theta(13) can, in general, remain valid even if the present 3 + 1 neutrino global fit data get ruled out by future experiments. We also discuss the possible implications at neutrinoless double beta decay (0 nu ss ss) experiments in view of the latest results from the KamLAND-Zen experiment.