Electron neutrino and antineutrino appearance in the full MINOS data sample

TL;DR

This analysis is the first use of this technique and includes the first accelerator long-baseline search for ν (μ) → ν(e), and the data disfavor 31% (5%) of the three-parameter space defined by δ, the octant of the θ23, and the mass hierarchy at the 68% (90%) C.L.

Abstract

We report on $ν_e$ and $\barν_e$ appearance in $ν_μ$ and $\barν_μ$ beams using the full MINOS data sample. The comparison of these $ν_e$ and $\barν_e$ appearance data at a 735 km baseline with $θ_{13}$ measurements by reactor experiments probes $δ$, the $θ_{23}$ octant degeneracy, and the mass hierarchy. This analysis is the first use of this technique and includes the first accelerator long-baseline search for $\barν_μ\rightarrow\barν_e$. Our data disfavor 31% (5%) of the three-parameter space defined by $δ$, the octant of the $θ_{23}$, and the mass hierarchy at the 68% (90%) C.L. We measure a value of 2sin$^2(2θ_{13})$sin$^2(θ_{23})$ that is consistent with reactor experiments.

Figures (4)

• Figure 1: Distributions of $\alpha_{LEM}$. The plots in the left column correspond to the $\nu$ beam mode. The plots in the right column correspond to the $\bar{\nu}$ beam mode. The top row shows the distributions for ND selected events with a band about the simulation representing the systematic uncertainty. The bottom row shows the distributions for the predicted FD background and signal multiplied by 10 with 2sin$^2(2\theta_{13})$sin$^2(\theta_{23})$$=$$0.1$, $\delta$$=$ 0, and a normal mass hierarchy.
• Figure 2: The reconstructed energy distributions for three $\alpha_{LEM}$ ranges. The events with energy greater than 5 GeV are combined into a single bin for the fits. The vertical bars through the data points denote statistical uncertainties. The signal predictions assume sin$^2$(2$\theta_{13}$) = 0.051, $\Delta m^{2}_{32}$$>$ 0, $\delta$ = 0, and $\theta_{23}$ = $\pi/4$. The plots in the left column correspond to data collected in the $\nu$ beam mode. The plots in the right column correspond to data collected in the $\bar{\nu}$ beam mode.
• Figure 3: The 68% and 90% confidence intervals of allowed values for 2sin$^2(2\theta_{13})$sin$^2(\theta_{23})$ as a function of $\delta$ for the two mass hierarchies.
• Figure 4: The resulting values of the likelihood $L$, shown here as $-2\Delta$ln$L$, from a fit of $\delta$ to our data using constraints from reactor experiments ref:DCref:DBref:RENO, assuming various values of the mass hierarchy and the sign of $\theta_{23}-\pi/4$. The difference is taken with respect to the best-fitting solution. Values above the horizontal dashed lines are disfavored at either 68% or 90% C.L.