Abstract

We report results from the first search for νμ→νe 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<δCP<0.5π in the inverted mass hierarchy at the 90% C.L.Received 19 January 2016DOI:https://doi.org/10.1103/PhysRevLett.116.151806© 2016 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino oscillationsSecondary beamsPropertiesCP symmetryTechniquesCalorimetersNeutrino detectionParticles & Fields