Dual baseline search for muon neutrino disappearance at $0.5{\mathrm{eV}}^2<\Delta m^2<40{\mathrm{eV}}^2$

The SciBooNE and MiniBooNE collaborations report the results of a ${\nu }_{\mu }$ disappearance search in the $\Delta m^2$ region of $0.5–40{\mathrm{eV}}^2$. The neutrino rate as measured by the SciBooNE tracking detectors is used to constrain the rate at the MiniBooNE Cherenkov detector in the first joint analysis of data from both collaborations. Two separate analyses of the combined data samples set 90% confidence level (CL) limits on ${\nu }_{\mu }$ disappearance in the $0.5–40{\mathrm{eV}}^2$ $\Delta m^2$ region, with an improvement over previous experimental constraints between 10 and $30{\mathrm{eV}}^2$.

Figure 1

(Top) Predicted number of CC events in the SciBar FV as a function of true $E_{\nu }$. The number of selected events in each subsample are also shown. (Bottom) Detection efficiency as a function of true neutrino energy for each subsample [20].

Figure 2

$E_{\nu }^{\mathrm{QE}}$ distribution for SciBooNE data (black) with statistical errors, and prediction assuming no oscillations (relatively normalized by the total number of SciBar-stopped and MRD-stopped events) for the SciBar-stopped sample (top) and MRD-stopped sample (bottom). Cosmic background is subtracted. Attached to the prediction is the size of the systematic uncertainties (shaded boxes). The predicted non-CCQE events (dash) are also shown.

Figure 3

(Top) $E_{\nu }^{\mathrm{QE}}$ distribution for MiniBooNE data (black) with statistical errors, and prediction assuming no oscillations for the simultaneous fit analysis (relatively normalized by the total number of SciBar-stopped and MRD-stopped events). Attached to the prediction is the size of the systematic uncertainties (shaded boxes). The predicted non-CCQE events (dash) are also shown. (Bottom) Same as above, for the spectrum fit analysis, where the prediction is scaled by the SciBooNE corrections.

Figure 4

Correlation coefficients of the total systematic uncertainties on the reconstructed $E_{\nu }$ distribution for the simultaneous fit analysis. Bins 0–15 and bins 16–31 are, respectively, for the SciBar-stopped and the MRD-stopped samples from SciBooNE, shown in Fig. 2. Bins 32–47 are for the MiniBooNE sample shown in the top panel of Fig. 3.

Figure 5

The fractional size of the systematic uncertainties for each MiniBooNE reconstructed $E_{\nu }$ bins for the spectrum fit analysis. The dashed lines show the uncertainties using MiniBooNE alone, and the solid lines show the uncertainties after the SciBooNE corrections.

Figure 6

Correlation coefficients of the total systematic uncertainties on the MiniBooNE reconstructed $E_{\nu }$ distribution for the spectrum fit analysis, shown in the right panel of Fig. 3.

Figure 7

Ratios with respect to the null hypothesis for SciBar-stopped (left), MRD-stopped (middle) and MiniBooNE (right) samples for the simultaneous fit analysis. Data (points), and disappearance expectations for the best fit (solid red) and parameters $\Delta m^2=1.0{\mathrm{eV}}^2$, ${sin}^{2}2\theta =0.5$ (dashed blue) and $\Delta m^2=10.0{\mathrm{eV}}^2$, ${sin}^{2}2\theta =0.5$ (dotted magenta) are shown. The best fit parameters are $\Delta m^2=43.7{\mathrm{eV}}^2$, ${sin}^{2}2\theta =0.60$. Fractional size of the diagonal elements of the error matrix for the null oscillation is shown as the gray bands.

Figure 8

Ratios with respect to the null hypothesis for MiniBooNE samples for the spectrum fit analysis. Data (points), and disappearance expectations for the best fit (solid red) and parameters $\Delta m^2=1.0{\mathrm{eV}}^2$, ${sin}^{2}2\theta =0.5$ (dashed blue) and $\Delta m^2=10.0{\mathrm{eV}}^2$, ${sin}^{2}2\theta =0.5$ (dotted magenta) are shown. The expectations are for the spectrum fit analysis. The best fit parameters are $\Delta m^2=41.7{\mathrm{eV}}^2$, ${sin}^{2}2\theta =0.51$. Fractional size of the diagonal elements of the error matrix for the null oscillation is shown as the gray bands.

Figure 9

The 90% CL limit for the simultaneous fit (solid, black curve), and for the spectrum fit (red, dashed curve). The sensitivity for the simultaneous fit analysis is also shown (dot-dash curve) with previous limits by CCFR [25] and CDHS [26] (light gray), MiniBooNE [11] (dark gray), and MINOS [27] (green-hash box). The sensitivity for the MiniBooNE-only analysis [11] is also shown (cyan, dashed curve).