Study of the wave packet treatment of neutrino oscillation at Daya Bay

Abstract

The disappearance of reactor (v) over bar (e) observed by the Daya Bay experiment is examined in the framework of a model in which the neutrino is described by a wave packet with a relative intrinsic momentum dispersion sigma(rel). Three pairs of nuclear reactors and eight antineutrino detectors, each with good energy resolution, distributed among three experimental halls, supply a high-statistics sample of (v) over bar (e) acquired at nine different baselines. This provides a unique platform to test the effects which arise from the wave packet treatment of neutrino oscillation. The modified survival probability formula was used to fit Daya Bay data, providing the first experimental limits: 2.38 x 10(-1)7 < sigma(rel) < 0.23. Treating the dimensions of the reactor cores and detectors as constraints, the limits are improved: 10-(14) less than or similar to sigma(rel) < 0.23, and an upper limit of sigma(rel) < 0.20 (which corresponds to sigma(x) greater than or similar to 10(-11) cm) is obtained. All limits correspond to a 95% C. L. Furthermore, the effect due to the wave packet nature of neutrino oscillation is found to be insignificant for reactor antineutrinos detected by the Daya Bay experiment thus ensuring an unbiased measurement of the oscillation parameters sin(2) 2 theta(13) and Delta m(32)(2) within the plane wave model.