Imprints of CP violation induced by sterile neutrinos in T2K data

We investigate the impact of light (∼eV) sterile neutrinos in the long-baseline experiment T2K. We show that, within the 3+1 scheme, for mass-mixing parameters suggested by the short-baseline anomalies, the interference among the sterile and the atmospheric oscillation frequencies induces a new term in the νμ→νe transition probability, which has the same order of magnitude of the standard 3-flavor solar-atmospheric interference term. We show, for the first time, that current T2K data, taken together with the results of the θ13-dedicated reactor experiments, are sensitive to two of the three CP-violating phases involved in the 3+1 scheme. Both the standard CP phase and the new one (δ13≡δ and δ14 in our parameterization choice) tend to have a common best-fit value δ13≃δ14≃-π/2. Quite intriguingly, the inclusion of sterile neutrino effects leads to better agreement between the two estimates of θ13 obtained, respectively, from reactors and T2K, which in the 3-flavor framework are slightly different.