The Double Chooz experiment has observed 8249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years ($\mathrm{\text{reactor power}}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{detector mass}}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{live time}}$) exposure using a $10.3\text{ }\text{ }{\mathrm{m}}^{3}$ fiducial volume detector located at 1050 m from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of ${\ensuremath{\theta}}_{13}=0$ is 8937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find ${sin}^{2}2{\ensuremath{\theta}}_{13}=0.109\ifmmode\pm\else\textpm\fi{}0.030(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.025(\mathrm{syst})$. The data exclude the no-oscillation hypothesis at 99.8% CL ($2.9\ensuremath{\sigma}$).

Reactor<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mover accent="true"><mml:mi>ν</mml:mi><mml:mo> ̄</mml:mo></mml:mover><mml:mi>e</mml:mi></mml:msub></mml:math>disappearance in the Double Chooz experiment

Reactorν ̄edisappearance in the Double Chooz experiment