Unexplained Excess of Electron-Like Events From a 1-GeV Neutrino Beam

The MiniBooNE Collaboration observes unexplained electron-like events in the reconstructed neutrino energy range from 200 to 475 MeV. With $6.46 \times 10^{20}$ protons on target, 544 electron-like events are observed in this energy range, compared to an expectation of $415.2 \pm 43.4$ events, corresponding to an excess of $128.8 \pm 20.4 \pm 38.3$ events. The shape of the excess in several kinematic variables is consistent with being due to either $\nu_e$ and $\bar \nu_e$ charged-current scattering or to $\nu_\mu$ neutral-current scattering with a photon in the final state. No significant excess of events is observed in the reconstructed neutrino energy range from 475 to 1250 MeV, where 408 events are observed compared to an expectation of $385.9 \pm 35.7$ events.Comment: Reduced length by 30 lines and made minor changes to reference

First Measurement of νμ\nu_\mu and νe\nu_e Events in an Off-Axis Horn-Focused Neutrino Beam

We report the first observation of off-axis neutrino interactions in the MiniBooNE detector from the NuMI beamline at Fermilab. The MiniBooNE detector is located 745 m from the NuMI production target, at 110 mrad angle ($6.3^{\circ}$) with respect to the NuMI beam axis. Samples of charged current quasi-elastic $\nu_{\mu}$ and $\nu_e$ interactions are analyzed and found to be in agreement with expectation. This provides a direct verification of the expected pion and kaon contributions to the neutrino flux and validates the modeling of the NuMI off-axis beam.Comment: 4 pages, 5 figures, Submitted to Phys. Rev. Let