RECENT RESULTS FROM DAYA BAY NEUTRINO EXPERIMENT

摘要

The Daya Bay Reactor Neutrino Experiment was designed to measure the smallest mixing angle θ_(13) in the three-neutrino mixing framework with unprecedented precision. In 2012, Daya Bay measured the first definitive non-zero value of θ_(13). Then, with more than 4 years' stable data taking, Daya Bay obtained the most precise value of sin~2 2θ_(13) and |Δm_(ee)~2|. In reactor antineutrino terms, the observed flux is consistent with measurements made by previous short baseline experiments, while the observed spectrum differs from prediction with a significance of 4.4σ in the 4-6 MeV energy region. Using our large reactor dataset, the experiment also measured the evolution of the reactor antineutrino flux and found that the IBD yield of ~(235)U is 7.8% lower than predicted. In sterile neutrino terms, there is no hint of a light sterile neutrino from Daya Bay data, giving the most stringent limit for |Δm_(41)~2| < 0.2 eV~2.