Impact of nuclear effects on the extraction of neutrino oscillation parameters

TL;DR

This paper investigates how nuclear effects and final state interactions can bias the measurement of neutrino oscillation parameters, especially the atmospheric mixing angle, in water Cherenkov detectors, highlighting the importance of accounting for these effects.

Contribution

It provides a detailed analysis of nuclear effects' impact on neutrino oscillation parameter extraction and emphasizes the need to consider these effects even with near detector data.

Findings

Nuclear effects can cause significant bias in atmospheric oscillation parameters.

Ignoring nuclear effects leads to biases comparable to statistical errors.

Including near detector data does not fully eliminate the bias.

Abstract

We study the possible impact of nuclear effects and final state interactions on the determination of the oscillation parameters due to mis-reconstruction of non-quasi-elastic events as quasi-elastic events at low energies. We analyze a $\nu_\mu$ disappearance experiment using a water \v{C}erenkov detector. We find that, if completely ignored in the fit, nuclear effects can induce a significant bias in the determination of atmospheric oscillation parameters, particularly for the atmospheric mixing angle. Even after inclusion of a near detector a bias in the determination of the atmospheric mixing angle comparable to the statistical error remains.