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تسجيل مستخدم جديدImproved Search for $bar u_mu rightarrow bar u_e$ Oscillations in the MiniBooNE Experiment
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The MiniBooNE experiment at Fermilab reports results from an analysis of $bar u_e$ 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 $200<E_ u^{QE}<1250$ MeV. If interpreted in a two-neutrino oscillation model, $bar{ u}_{mu}rightarrowbar{ u}_e$, 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.
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The MiniBooNE experiment at Fermilab reports results from a search for $bar u_mu rightarrow bar u_e$ 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 en
ergy range $475<E_ u^{QE}<1250$ MeV, which, when constrained by the observed $bar u_mu$ events, has a probability for consistency with the background-only hypothesis of 0.5%. On the other hand, fitting for $bar{ u}_{mu}rightarrowbar{ u}_e$ oscillations, the best-fit point has a $chi^2$-probability of 8.7%. The data are consistent with $bar u_mu rightarrow bar u_e$ oscillations in the 0.1 to 1.0 eV$^2$ $Delta m^2$ range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.
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