Significant Excess of Electronlike Events in the MiniBooNE Short-Baseline Neutrino Experiment

Abstract

The MiniBooNE experiment at Fermilab reports results from an analysis of νe appearance data from 12.84 × 10 20 protons on target in neutrino mode, an increase of approximately a factor of two over previously reported results. A νe charged-current quasielastic event excess of 381.2 ± 85.2 events (4.5σ) is observed in the energy range 200 < E QE ν < 1250 MeV. Combining these data with theνe appearance data from 11.27 × 10 20 protons on target in antineutrino mode, a total νe plus νe charged-current quasielastic event excess of 460.5 ± 99.0 events (4.7σ) is observed. If interpreted in a two-neutrino oscillation model, νµ → νe, the best oscillation fit to the excess has a probability of 21.1%, while the background-only fit has a χ 2 probability of 6 × 10 −7 relative to the best fit. The MiniBooNE data are consistent in energy and magnitude with the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND), and the significance of the combined LSND and MiniBooNE excesses is 6.0σ. A two-neutrino oscillation interpretation of the data would require at least four neutrino types and indicate physics beyond the three neutrino paradigm. Although the data are fit with a two-neutrino oscillation model, other models may provide better fits to the data.Evidence for short-baseline neutrino anomalies at an L/E ν ∼ 1 m/MeV, where E ν is the neutrino energy and L is the distance that the neutrino traveled before detection, comes from both neutrino appearance and disappearance experiments. The appearance anomalies include the excess of ν e andν e charge-current quasielastic (CCQE) events observed by the LSND [1] and MiniBooNE [2,3] experiments, while the disappearance anomalies, although not completely consistent, include the deficit of ν e andν e events observed by reactor [4] and radioactive-source experiments [5]. As the masses and mixings within the 3-generation neutrino matrix have been attached to solar and long-baseline neutrino experiments, more exotic models are typically used to explain these anomalies, including, for example, 3+N neutrino oscillation models involving three active neutrinos and N additional sterile neutrinos [6][7][8][9][10][11][12][13][14], resonant neutrino oscillations [15], Lorentz violation [16], sterile neutrino decay [17], sterile neutrino nonstandard interactions [18], and sterile neutrino extra dimensions [19]. This Letter presents improved MiniBooNE ν e andν e appearance results, assuming two-neutrino oscillations with probability arXiv:1805.12028v2 [hep-ex]

Inflation models in the light of self-interacting sterile neutrinos

“…This was pointed out by the LSND experiment [1], where an excess of electron like events was reported inν µ →ν e oscillations. Similar kind of excess has also been reported in both the neutrino and anti-neutrino channels by the MiniBoone experiment recently [2][3][4]. There are a few other experiments which have also reported similar anomalies [5][6][7].…”

Impact of Active-Sterile Neutrino Mixing at Currently Running Long-Baseline Experiments

“…Similar anomalies have also been observed at GALLEX and SAGE Gallium experiments for solar neutrino observation, which also indicate the existence of additional light neutrino species [8,9]. Recently MiniBooNE collaboration [10], reported their new analysis with twice the data sample size used earlier, confirming the anomaly at the level of 4.8σ, which becomes > 6σ, if combined with LSND data. Though an eV scale neutrino can explain all these anomalies, such a neutrino cann't have gauge interactions with the SM gauge bosons, to satisfy the precision measurement of Z boson decay width at LEP experiment.…”

The radial acceleration relation in galaxy clusters

“…Adding sterile neutrinos to MOND might be able to account for the RAR in galaxy clusters because the 'baryonic mass' could be increased by a certain factor such that the empirical RAR would be fitted to the galaxy cluster data with the canonical value of a0. The possibility of the existence of massive sterile neutrinos is hinted by some ground-based experiments (Aguilar-Arevalo et al 2018) and now becoming a hot issue in particle physics. It is also possible to have some connections between MOND and long-range quantum gravity (Cadoni & Tuveri 2019).…”