Search for Sub-eV Sterile Neutrinos at RENO

Abstract

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 ((nu) over bar (e)) disappearance taking place between six 2.8GW(th) 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 (nu) over bar (e) 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 sin(2) 2 theta(14) in the 10(-4) less than or similar to vertical bar Delta m(41)(2)vertical bar less than or similar to 0.5 eV(2) region, free from reactor (nu) over bar (e) flux and spectrum uncertainties. The RENO result provides the most stringent limits on sterile neutrino mixing at vertical bar Delta m(41)(2)vertical bar less than or similar to 0.002 eV(2) using the (nu) over bar (e) disappearance channel.