Method for determination of |Ue3| in neutrino oscillation appearance experiments

Abstract We point out that determination of the MNS matrix element | U e 3 |= s 13 in long-baseline ν μ → ν e neutrino oscillation experiments suffers from large intrinsic uncertainty due to the unknown CP violating phase δ and sign of Δm 2 13 . We propose a new strategy for accurate determination of θ 13 ; tune the beam energy at the oscillation maximum and do the measurement both in neutrino and antineutrino channels. We show that it automatically resolves the problem of parameter ambiguities which involves δ , θ 13 , and the sign of Δm 2 13 .