arXiv subjects

The MiniBooNE Collaboration

Publications and source records attributed to The MiniBooNE Collaboration.

8 recordsLinked to original sources

arXiv2013

Improved Search for $\bar \nu_\mu \rightarrow \bar \nu_e$ Oscillations in the MiniBooNE Experiment

The MiniBooNE experiment at Fermilab reports results from an analysis of $\bar \nu_e$ appearance data from $11.27 \times 10^{20}$ protons on target in antineutrino mode, an increase of approximately a factor of two over the previously reported results. An event excess of $78.4 \pm 28.5$ events ($2.8 \sigma$) is observed in the energy range $200<E_\nu^{QE}<1250$ MeV. If interpreted in a two-neutrino oscillation model, $\bar{\nu}_{\mu}\rightarrow\bar{\nu}_e$, the best oscillation fit to the excess has a probability of 66% while the background-only fit has a $\chi^2$-probability of 0.5% relative to the best fit. The data are consistent with antineutrino oscillations in the $0.01 < \Delta m^2 < 1.0$ eV$^2$ range and have some overlap with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector (LSND). All of the major backgrounds are constrained by in-situ event measurements so non-oscillation explanations would need to invoke new anomalous background processes. The neutrino mode running also shows an excess at low energy of $162.0 \pm 47.8$ events ($3.4 \sigma$) 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.

hep-ex↗

arXiv2012

Test of Lorentz and CPT violation with Short Baseline Neutrino Oscillation Excesses

The sidereal time dependence of MiniBooNE electron neutrino and anti-electron neutrino appearance data are analyzed to search for evidence of Lorentz and CPT violation. An unbinned Kolmogorov-Smirnov test shows both the electron neutrino and anti-electron neutrino appearance data are compatible with the null sidereal variation hypothesis to more than 5%. Using an unbinned likelihood fit with a Lorentz-violating oscillation model derived from the Standard Model Extension (SME) to describe any excess events over background, we find that the electron neutrino appearance data prefer a sidereal time-independent solution, and the anti-electron neutrino appearance data slightly prefer a sidereal time-dependent solution. Limits of order 10E-20 GeV are placed on combinations of SME coefficients. These limits give the best limits on certain SME coefficients for muon neutrino to electron neutrino and anti-muon neutrino to anti-electron neutrino oscillations. The fit values and limits of combinations of SME coefficients are provided.

hep-ex↗

arXiv2010

Event Excess in the MiniBooNE Search for $\bar ν_μ\rightarrow \bar ν_e$ Oscillations

The MiniBooNE experiment at Fermilab reports results from a search for $\bar ν_μ\rightarrow \bar ν_e$ oscillations, using a data sample corresponding to $5.66 \times 10^{20}$ protons on target. An excess of $20.9 \pm 14.0$ events is observed in the energy range $475<E_ν^{QE}<1250$ MeV, which, when constrained by the observed $\bar ν_μ$ events, has a probability for consistency with the background-only hypothesis of 0.5\%. On the other hand, fitting for $\barν_μ\rightarrow\barν_e$ oscillations, the best-fit point has a $χ^2$-probability of 8.7\%. The data are consistent with $\bar ν_μ\rightarrow \bar ν_e$ oscillations in the 0.1 to 1.0 eV$^2$ $Δm^2$ range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.

hep-ex↗

arXiv2010

Measurement of the Neutrino Neutral-Current Elastic Differential Cross Section

We report a measurement of the flux-averaged neutral-current elastic differential cross section for neutrinos scattering on mineral oil (CH$_2$) as a function of four-momentum transferred squared. It is obtained by measuring the kinematics of recoiling nucleons with kinetic energy greater than 50~MeV which are readily detected in MiniBooNE. This differential cross-section distribution is fit with fixed nucleon form factors apart from an axial mass, $M_{A}$, that provides a best fit for $M_A= 1.39\pm0.11$~GeV. Additionally, single protons with kinetic energies above 350 MeV can be distinguished from neutrons and multiple nucleon events. Using this marker, the strange quark contribution to the neutral-current axial vector form factor at $Q^2 = 0$, $Δs$, is found to be $Δs=0.08\pm0.26$.

hep-ex↗

arXiv2010

Measurement of ν_μand \barν_μinduced neutral current single $π^0$ production cross sections on mineral oil at E_νO(1 GeV)

MiniBooNE reports the first absolute cross sections for neutral current single π^0 production on CH_2 induced by neutrino and antineutrino interactions measured from the largest sets of NC π^0 events collected to date. The principal result consists of differential cross sections measured as functions of π^0 momentum and π^0 angle averaged over the neutrino flux at MiniBooNE. We find total cross sections of (4.76+/-0.05_{stat}+/-0.76_{sys})*10^{-40} cm^2/nucleon at a mean energy of =808 MeV and (1.48+/-0.05_{stat}+/-0.23_{sys})*10^{-40} cm^2/nucleon at a mean energy of =664 MeV for ν_μand \barν_μinduced production, respectively. In addition, we have included measurements of the neutrino and antineutrino total cross sections for incoherent exclusive NC 1π^0 production corrected for the effects of final state interactions to compare to prior results.

hep-ex↗

arXiv2008

Compatibility of high-$Δ\mathrm{m}^2$ $\nue$ and $\nuebar$ neutrino oscillation searches

This article presents the compatibility of experimental data from neutrino oscillation experiments with a high-$\dmsq$ two-neutrino oscillation hypothesis. Data is provided by the Bugey, Karlsruhe Rutherford Medium Energy Neutrino Experiment 2 (KARMEN2), Los Alamos Liquid Scintillator Neutrino Detector (LSND), and MiniBooNE experiments. The LSND, KARMEN2, and MiniBooNE results are 25.36% compatible within a two-neutrino oscillation hypothesis. However, the point of maximal compatibility is found in a region that is excluded by the Bugey data. A joint analysis of all four experiments, performed in the $\sinsqtheta \mathrm{vs} \dmsq$ region common to all data, finds a maximal compatibility of 3.94%. This result does not account for additions to the neutrino oscillation model from sources such as CP violation or sterile neutrinos.

hep-ex↗

arXiv2008

First Observation of Coherent $π^0$ Production in Neutrino Nucleus Interactions with $E_ν<$ 2 GeV

The MiniBooNE experiment at Fermilab has amassed the largest sample to date of $π^0$s produced in neutral current (NC) neutrino-nucleus interactions at low energy. This paper reports a measurement of the momentum distribution of $π^0$s produced in mineral oil (CH$_2$) and the first observation of coherent $π^0$ production below 2 GeV. In the forward direction, the yield of events observed above the expectation for resonant production is attributed primarily to coherent production off carbon, but may also include a small contribution from diffractive production on hydrogen. Integrated over the MiniBooNE neutrino flux, the sum of the NC coherent and diffractive modes is found to be (19.5 $\pm$1.1 (stat) $\pm$2.5 (sys))% of all exclusive NC $π^0$ production at MiniBooNE. These measurements are of immediate utility because they quantify an important background to MiniBooNE's search for $ν_μ \to ν_e$ oscillations.

hep-ex↗

arXiv2007

A Search for Electron Neutrino Appearance at the Delta m2 ~ 1 eV2 Scale

The MiniBooNE Collaboration reports first results of a search for $ν_e$ appearance in a $ν_μ$ beam. With two largely independent analyses, we observe no significant excess of events above background for reconstructed neutrino energies above 475 MeV. The data are consistent with no oscillations within a two neutrino appearance-only oscillation model.

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