Search for Sub-eV Sterile Neutrinos at RENO

We report a search result for a light sterile neutrino oscillation with roughly 2200 live days of data in the RENO experiment. The search is performed by electron antineutrino (νₑ) disappearance taking place between six 2.8 GWₜₕ reactors and two identical detectors located at 294 m (near) and 1383 m (far) from the center of the reactor array. A spectral comparison between near and far detectors can explore reactor νₑ oscillations to a light sterile neutrino. An observed spectral difference is found to be consistent with that of the three-flavor oscillation model. This yields limits on sin²2θ₁₄ in the 10^-4|Δm₄₁²|0.5 eV² region, free from reactor νₑ flux and spectrum uncertainties. The RENO result provides the most stringent limits on sterile neutrino mixing at |Δm₄₁²|0.002 eV² using the νₑ disappearance channel.