From 1995, the LSND experiment looked for νe in a νμ neutrino beam produced at the Los Alamos laboratory. The result was the observation of an excess of νe interpreted as neutrino oscillation with parameters (Δm2 ~ 1eV2) not compatible with other experiments for a two neutrino oscillation [Ath95]. The final result in 2001 confirmed the excess [Agu01]. They interpreted their result by the existence of a sterile neutrino of mass greater than 0.4 eV.
The MiniBooNE experiment was set up at Fermilab to confirm or infirm the LSND result. Their 2007 result excluded an oscillation νμ to νe [Agu07], but their 2010 result finds an oscillation νμ to νe compatible with that of LSND [Agu10].
The results of LSND and MiniBooNE are still controversial, since cosmological observations tend to disagree with their conclusion on the existence of a fourth neutrino.
|Ath95||C. Athanassopoulos et al., LSND collaboration||Candidate events for antineutrino muon - antineutrino electron oscillations||Phys. Rev. Lett. 75 (1995) 2650|
|Agu01||A. Aguilar et al., LSND collaboration||Evidence for neutrino oscillations from the observation of antineutrino electron appearance in an antineutrino muon beam||Phys. Rev. D64 (2001) 112007; arXiv:hep-ex/0104049|
|Are07||A.A. Aguilar Arevalo et al., MiniBooNE collaboration||Search for electron neutrino appearance at the Dm2 ~ 1 eV2||Phys. Rev. Lett. 98 (2007) 231801; arXiv:0704.1500|
|Agu10||A.A. Aguilar Arevalo et al., MiniBooNE collaboration||Event excess in the MiniBooNE search for muon antineutrino to electron antineutrino||Phys. Rev. Lett. 105 (2010) 181801; arXiv:1007.1150|