Impact of Nuclear effects in Energy Reconstruction Methods on Sensitivity of Neutrino Oscillation Parameters at NO$\nu$A experiment

Abstract

Long baseline (LBL) neutrino experiments aim to measure the neutrino oscillation parameters to high precision. These experiments use nuclear targets for neutrino scattering and hence are inflicted with complexities of nuclear effects. Nuclear effects and their percolation into sensitivity measurement of neutrino oscillations parameters are not yet fully understood and therefore need to be dealt with carefully. In a recent work [1], we reported some results on this for NO$\nu$A experiment using the kinematic method of neutrino energy reconstruction, where it was observed that the nuclear effects are important in sensitivity analysis, and inclusion of realistic detector setup specifications increases uncertainty in this analysis as compared to ideal detector case. With this motivation, in this work, we use two methods of neutrino energy reconstruction - kinematic and calorimetric, including the nuclear effects, and study their impact on sensitivity analysis. We consider nuclear interactions such as RPA and 2p2h and compare two energy reconstruction methods with reference to events generation, measurement of neutrino oscillation parameters $\Delta m_{32}^2$ and $\theta_{23}$ for disappearance channel, mass hierarchy sensitivity, and CP-violation sensitivity for appearance channel of the NO$\nu$A experiment. It is observed that with an ideal detector setup, the kinematic method shows significant dependence on nuclear effects compared to the calorimetric method. We also investigate the impact of realistic detector setup for NO$\nu$A in these two methods (with nuclear effects) and find that the calorimetric method shows more bias (uncertainty increases) in sensitivity contours, as compared to the kinematic method. This is found to be true for both the mass hierarchies and for both neutrino and antineutrino incoming beams.