Energy Reconstruction in the Long-Baseline Neutrino Experiment

The Long-Baseline Neutrino Experiment aims at measuring fundamental physical parameters to high precision and exploring physics beyond the standard model. Nuclear targets introduce complications towards that aim. We investigate the uncertainties in the energy reconstruction, based on quasielastic scattering relations, due to nuclear effects. The reconstructed event distributions as a function of energy tend to be smeared out and shifted by several 100 MeV in their oscillatory structure if standard event selection is used. We show that a more restrictive experimental event selection offers the possibility to reach the accuracy needed for a determination of the mass ordering and the $CP$-violating phase. Quasielastic-based energy reconstruction could thus be a viable alternative to the calorimetric reconstruction also at higher energies.

Figure 1

Flux distribution for LBNE, normalized to 1 in the full energy regime $0\le E\le 30\mathrm{GeV}$. The distribution is taken from [19].

Figure 2

Event distribution (normalized flux times cross section) per nucleon for LBNE vs. true (solid curve) and reconstructed (dashed curve) energy. The upper two (red) curves give the distribution without oscillation, the lower two (black) curves give the distribution with oscillation in the muon disappearance channel. In the upper part of the figure, the events have no pions in the final state; in the lower part the events have 0 pions, exactly 1 proton, and $X$ neutrons in the final state.

Figure 3

Survival probability for $\mu$ neutrinos both for true (solid) and reconstructed (dashed) energies for 0-pion events. The dotted curve gives the probability for events with 0 pions, 1 proton, and $X$ neutrons.

Figure 4

Event distribution per nucleon for electron appearance both for true (solid) and reconstructed (dashed) energies. The $CP$-violating phase has been set to 0. The upper two curves are based on 0 pion events, the lower two curves on events with 0 pions, 1 proton, and $X$ neutrons.

Figure 5

Event distributions per nucleon for electron appearance for ${\delta }_{CP}=+\pi /2$ and ${\delta }_{CP}=-\pi /2$ (upper red and lower black curves, respectively), both for true (solid) and reconstructed (dashed) energies. The upper part gives the results for 0-pion events, the lower part gives the results for events with 0 pions, 1 proton, and $X$ neutrons.