Constraints on Light Sterile Neutrinos and Scalar Non-Standard Interactions Using the First Reactor Antineutrino Oscillation Results at JUNO

Abstract

Constraints on light sterile neutrinos and scalar non-standard neutrino interactions are obtained from the first reactor antineutrino results reported by JUNO. The analysis is based on a spectral $χ^2$ fit to the prompt-energy distribution corresponding to 59.1 days of data, including full three-flavor oscillations extended to a $3+1$ framework and effective scalar NSI contributions. The reactor flux is modeled using the Daya Bay measured spectrum, and systematic uncertainties are accounted for through a set of nuisance parameters describing reactor flux normalization, spectral shape, background normalization, and detector response. It is found that JUNO is already sensitive to light sterile neutrinos in the mass-splitting range $10^{-5} \lesssim Δm^2_{41}/\text{eV}^2 \lesssim 10^{-2}$, probing mixing amplitudes down to $\sin^2 2θ_{14} \sim \mathcal{O}(10^{-1})$. In addition, a constraint on the scalar NSI parameter $|η_{ee}| < \mathcal{O}(10^{-2})$ is obtained, with correlations with solar oscillation parameters. These results demonstrate the potential of JUNO to probe small deviations from the Standard Model resulting from new physics through precision measurements, with significant improvements expected as statistics and systematic control improve.

Figures (2)

• Figure 1: 95% CL exclusion contour for the neutrino oscillation parameters $\sin^2 \theta_{14}$ and $\Delta m^2_{41}$, assuming normal mass ordering. The constraints obtained from the JUNO data analyzed in this work are presented (black), as well as limits from KamLAND Chen2022, Daya Bay An2014, and RENO Choi2020.
• Figure 2: $\Delta\chi^2$ profile of the scalar $\eta_{ee}$ parameter obtained in this work. Results from Borexino Ge:2018uhz are also shown, together with the expected sensitivity from DUNE Singha:2023set.