Non-standard interaction in neutrino oscillations and recent Daya Bay, T2K experiments

Abstract

We study the possible constraints on non-standard interaction(NSIs) in a model independent way by considering the recent results from T2K and Daya Bay neutrino oscillations experiments. Using perturbation method we present generic formulas (suitable for T2K baseline and for large $θ_{13}$ as evident from Daya Bay) for the probability of oscillation for $ν_μ\rightarrow ν_e$, taking into account NSIs at source ($ε^s$), detector ($ε^d$) and during propagation ($ε^m$) of neutrinos through matter. Two separate cases of perturbation with small (slightly large) NSI ($ε_{αβ}^m \sim 0.03(0.18)$) are discussed in detail. Using various possible presently allowed NSI values we reanalyze numerically the $θ_{13} - δ$ allowed region given by recent T2K experimental data. We obtain model independent constraints on NSIs in the $δ-ε_{αβ}^m$ plane using the $θ_{13}$ value as measured by Daya Bay, where $δ$ is the CP violating phase. Depending on $δ$ values significant constraints on $ε_{eτ}$ and $ε_{ττ}$, in particular, are possible for both hierarchies of neutrino masses. Corresponding to T2K's 66% confidence level result, the constraints on $ε_{ττ}$ is shown to be independent of any $δ$ value.