Background-independent measurement of theta(13) in Double Chooz


The oscillation results published by the Double Chooz Collaboration in 2011 and 2012 rely on background models substantiated by reactor-on data. In this analysis, we present a background-model-independent measurement of the mixing angle (\theta_{13}) by including 7.53 days of reactor-off data. A global fit of the observed antineutrino rates for different reactor power conditions is performed, yielding a measurement of both (\theta_{13}) and the total background rate. The results on the mixing angle are improved significantly by including the reactor-off data in the fit, as it provides a direct measurement of the total background rate. This reactor rate modulation analysis considers antineutrino candidates with neutron captures on both Gd and H, whose combination yields sin² (2(\theta_{13}))=0.102±0.028(stat.)±0.033(syst.). The results presented in this study are fully consistent with the ones already published by Double Chooz, achieving a competitive precision. They provide, for the first time, a determination of (\theta_{13}) that does not depend on a background model.

Astronomy & Astrophysics, Physics, Nuclear, Physics, Particles & Fields, Physics
Abe, Y., dos Anjos, J. C., Barriere, J. C., Baussan, E., Bekman, I., Bergevin, M., Bezerra, T. J. C., Bezrukov, L., Blucher, E., Buck, C., Busenitz, J., Cabrera, A., Caden, E., Camilleri, L., Carr, R., Cerrada, M., Chang, P.-J., Chauveau, E., Chimenti, P., … Zimmer, V. (2014). Background-independent measurement of <mml:math altimg="si1.gif" overflow="scroll" xmlns:xocs="" xmlns:xs="" xmlns:xsi="" xmlns="" xmlns:ja="" xmlns:mml="" xmlns:tb="" xmlns:sb="" xmlns:ce="" xmlns:xlink="" xmlns:cals="" xmlns:sa=""><mml:msub><mml:mrow><mml:mi>θ</mml:mi></mml:mrow><mml:mrow><mml:mn>13</mml:mn></mml:mrow></mml:msub></mml:math> in Double Chooz. In Physics Letters B (Vol. 735, pp. 51–56). Elsevier BV.