Search for active-sterile neutrino mixing using neutral-current interactions in NOvA

We report results from the first search for sterile neutrinos mixing with active neutrinos through a reduction in the rate of neutral-current interactions over a baseline of 810 km between the NOvA detectors. Analyzing a 14-kton detector equivalent exposure of 6.05 × 1020 protons-on-target in the NuMI beam at Fermilab, we observe 95 neutral-current candidates at the Far Detector compared with 83.5±9.7(stat)±9.4(syst) events predicted assuming mixing only occurs between active neutrino species. No evidence for ?µ ? ?s transitions is found. Interpreting these results within a 3+1 model, we place constraints on the mixing angles ?24 < 20.8° and ?34 < 31.2° at the 90% C.L. for 0.05 eV2 = ?m2 41 = 0.5 eV2, the range of mass splittings that produce no significant oscillations over the Near Detector baseline.