Measurement of Effective $\Delta m_{31}^2$ using Baseline Differences of Daya Bay, RENO and Double Chooz Reactor Neutrino Experiments

TL;DR

This paper measures the effective m_{31}^2 neutrino oscillation parameter using baseline differences from three reactor experiments, providing a new approach that complements spectrum distortion methods and aligns with accelerator results.

Contribution

It introduces a baseline-based method to determine m_{31}^2, offering an alternative to energy spectrum distortion measurements and addressing calibration challenges.

Findings

m_{31}^2 measured as 2.99^{+1.13}_{-1.58} imes 10^{-3} eV^2

Results are consistent with accelerator m_{32}^2 measurements

Method demonstrates potential for future neutrino oscillation studies

Abstract

In 2011 and 2012, three reactor neutrino experiments, Double Chooz, Daya Bay and RENO showed positive signals of reactor neutrino disappearance and measured a mixing parameter sin^2(2th13) at average baselines 1.05, 1.65 and 1.44km, respectively. It is possible to measure effective Dm31^2 from distortion of neutrino energy spectrum (E dependence of the oscillation) in those experiments. However, since it requires a precise energy calibration, such measurements have not been reported yet. Dm31^2 can also be measured from baseline (L) dependence of the neutrino oscillation. In this paper, Dm31^2 is measured from disappearance probabilities of the three reactor experiments which have different baselines, to be 2.99^{+1.13}_{-1.58}(^{+0.86}_{-0.88}) X 10^{-3}eV^2, where the errors are two (one) dimensional uncertainties. This is consistent with Dm32^2 measured by \nu_{\mu} disappearance in accelerator experiments. Importance of Dm31^2 measurement and future possibilities are also discussed.