A Global Fit Determination of Effective $\Delta m_{31}^2$ from Baseline Dependence of Reactor $\bar{\nu}_e$ Disappearance

TL;DR

This paper performs a global fit to reactor neutrino data to measure the effective mass-squared difference Δm_{31}^2, providing results consistent with other neutrino experiments and demonstrating the consistency of reactor neutrino measurements.

Contribution

It introduces a comprehensive global fit method to determine the effective Δm_{31}^2 from baseline dependence, complementing spectrum shape analyses.

Findings

Measured Δm_{31}^2 = 2.95^{+0.42}_{-0.61} × 10^{-3} eV^2

Determined sin^2 2θ_{13} = 0.099^{+0.016}_{-0.012}

Results are consistent with other neutrino oscillation measurements.

Abstract

Recently, three reactor neutrino experiments, Daya Bay, Double Chooz and RENO have directly measured the neutrino mixing angle $\theta_{13}$. In this paper, another important oscillation parameter, effective $\Delta m_{31}^2$ (= $\Delta \tilde{m}_{31}^2$) is measured using baseline dependence of the reactor neutrino disappearance. A global fit is applied to publicly available data and $\Delta \tilde{m}_{31}^2 = 2.95^{+0.42}_{-0.61} \times 10^{-3}$ eV$^2$, $\sin^22\theta_{13} = 0.099^{+0.016}_{-0.012}$ are obtained by setting both parameters free. This result is complementary to $\Delta tilde{m}_{31}^2$ to be measured by spectrum shape analysis. The measured $\Delta \tilde{m}_{31}^2$ is consistent with $\Delta \tilde{m}_{32}^2$ measured by $\nu_{\mu}$ disappearance in MINOS, T2K and atmospheric neutrino experiments within errors. The minimum $\chi^2$ is small, which means the results from the three reactor neutrino experiments are consistent with each other.