First Measurement of Electron Neutrino Appearance in NOvA


We report results from the first search for ν_μ → ν_e transitions by the NOvA experiment. In an exposure equivalent to 2.74 × 10²⁰ protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99 ± 0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07 ± 0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π < δ_{CP} < 0.5π in the inverted mass hierarchy at the 90% C.L.;



Neutrinos, Proton beams, Calorimeters, Symmetry (Physics), Fermi National Accelerator Laboratory


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