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 ${\theta }_{13}$ as evident from Daya Bay) for the probability of oscillation for ${\nu }_{\mu }\to {\nu }_e$, 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 (${ϵ}_{\alpha \beta }^m\sim 0.03(0.18)$) are discussed in detail. Using various possible presently allowed NSI values we reanalyze numerically the ${\theta }_{13}-\delta$ allowed region given by recent T2K experimental data. We obtain model independent constraints on NSIs in the $\delta -{ϵ}_{\alpha \beta }^m$ plane using the ${\theta }_{13}$ value as measured by Daya Bay, where $\delta$ is the CP violating phase. Depending on $\delta$ values significant constraints on ${ϵ}_{e\tau }$ and ${ϵ}_{\tau \tau }$, in particular, are possible for both hierarchies of neutrino masses. Corresponding to T2K's 66% confidence level result, the constraints on ${ϵ}_{\tau \tau }$ is shown to be independent of any $\delta$ value.

Comments: 13 pages, RevTex4, 6 figures (12 eps files) Significant changes after incorporating Daya Bay result