科研之友
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摘要
We discuss the possibility to explain the anomalies in short-baseline neutrino oscillation experiments in terms of sterile neutrinos. We work in a 3+1 framework and pay special attention to recent new data from reactor experiments, IceCube and MINOS+. We find that results from the DANSS and NEOS reactor experiments support the sterile neutrino explanation of the reactor anomaly, based on an analysis that relies solely on the relative comparison of measured reactor spectra. Global data from the nu(e) disappearance channel favour sterile neutrino oscillations at the 3 sigma level with Delta m(41)(2) approximate to 1.3 eV(2) and vertical bar U-e4 vertical bar approximate to 0.1, even without any assumptions on predicted reactor fluxes. In contrast, the anomalies. in the nu(e) appearance channel (dominated by LSND) are in strong tension with improved bounds on nu(mu) disappearance, mostly driven by MINOS+ and IceCube. Under the sterile neutrino oscillation hypothesis, the p-value for those data sets being consistent is less than 2.6 x 10(-6). Therefore, an explanation of the LSND anomaly in terms of sterile neutrino oscillations in the 3+1 scenario is excluded at the 4.7 sigma level. This result is robust with respect to variations in the analysis and used data, in particular it depends neither on the theoretically predicted reactor neutrino fluxes, nor on constraints from any single experiment. Irrespective of the anomalies, we provide updated constraints on the allowed mixing strengths vertical bar U-alpha 4 vertical bar (alpha = e, mu, tau) of active neutrinos with a fourth neutrino mass state in the eV range.
- 出版日期2018-8-3
