Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 04510 México, D.F., Mexico.
Phys Rev Lett. 2013 Apr 19;110(16):161801. doi: 10.1103/PhysRevLett.110.161801. Epub 2013 Apr 15.
The MiniBooNE experiment at Fermilab reports results from an analysis of νover ¯ appearance data from 11.27×10(20) protons on target in the antineutrino mode, an increase of approximately a factor of 2 over the previously reported results. An event excess of 78.4±28.5 events (2.8σ) is observed in the energy range 200<E(ν)(QE)<1250 MeV. If interpreted in a two-neutrino oscillation model, νover ¯→νover ¯, the best oscillation fit to the excess has a probability of 66% while the background-only fit has a χ(2) probability of 0.5% relative to the best fit. The data are consistent with antineutrino oscillations in the 0.01<Δm(2)<1.0 eV(2) range and have some overlap with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector. All of the major backgrounds are constrained by in situ event measurements so nonoscillation explanations would need to invoke new anomalous background processes. The neutrino mode running also shows an excess at low energy of 162.0±47.8 events (3.4σ) but the energy distribution of the excess is marginally compatible with a simple two neutrino oscillation formalism. Expanded models with several sterile neutrinos can reduce the incompatibility by allowing for CP violating effects between neutrino and antineutrino oscillations.
MiniBooNE 实验在费米实验室报告了中微子反中微子模式下 11.27×10(20)个质子靶实验数据分析结果，与之前报道的结果相比，这一结果增加了约两倍。在 200<E(ν)(QE)<1250 MeV 的能量范围内，观察到 78.4±28.5 个事件（2.8σ）的事件过剩。如果用双中微子振荡模型解释，νover ¯→νover ¯，则对过剩的最佳振荡拟合概率为 66%，而仅背景拟合的 χ(2)概率为 0.5%，相对于最佳拟合。数据与 0.01<Δm(2)<1.0 eV(2)范围内的反中微子振荡一致，并且与液体闪烁体中微子探测器的反中微子振荡证据有一些重叠。所有主要的背景都受到现场事件测量的限制，因此非振荡解释将需要引入新的异常背景过程。中微子模式运行也显示在低能区有 162.0±47.8 个事件（3.4σ）的过剩，但过剩的能量分布与简单的双中微子振荡形式主义基本兼容。具有几个惰性中微子的扩展模型可以通过允许中微子和反中微子振荡之间的 CP 破坏效应来降低不兼容性。
