Four-neutrino analysis of 1.5km-baseline reactor antineutrino oscillations

TL;DR

This paper analyzes reactor antineutrino data from RENO and Daya Bay using a four-neutrino model to explore sterile neutrino parameters and their impact on known oscillation angles.

Contribution

It provides the first four-neutrino analysis of these experiments, including exclusion limits on sterile neutrino parameters and their effect on the measurement of θ13.

Findings

Excluded regions for Δm^2_41 and θ14.

Adjusted θ13 values considering sterile neutrino mixing.

Consistent θ13 measurements within 1σ when including sterile neutrinos.

Abstract

The masses of sterile neutrinos are not yet known, and depending on the orders of magnitudes, their existence may explain reactor anomalies or the spectral shape of reactor neutrino events at 1.5km-baseline detector. Here, we present four-neutrino analysis of the results announced by RENO and Daya Bay, which performed the definitive measurements of $\theta_{13}$ based on the disappearance of reactor antineutrinos at km-order baselines. Our results using 3+1 scheme include the exclusion curve of $\Delta m^2_{41}$ vs. $\theta_{14}$ and the adjustment of $\theta_{13}$ due to correlation with $\theta_{14}$. The value of $\theta_{13}$ obtained by RENO and Daya Bay with a three-neutrino oscillation analysis is included in the $1\sigma$ interval of $\theta_{13}$ allowed by our four-neutrino analysis.