Systematic Uncertainties and Cross-Checks for the NOvA Joint $\nu_\mu$+$\nu_e$ Analysis

TL;DR

This paper discusses the systematic uncertainties and validation methods used in the NOvA neutrino oscillation analysis to ensure accurate measurement of neutrino parameters.

Contribution

It provides a detailed overview of the systematic uncertainty treatment and cross-check procedures specific to the NOvA joint neutrino analysis.

Findings

Systematic uncertainties are rigorously modeled and propagated.

Cross-checks include muon removed simulations and cosmic muon bremsstrahlung.

Results support the normal hierarchy preference.

Abstract

The physics goals of NOvA are the constraints of neutrino oscillation parameters such as the octant of $\theta_{23}$, $\delta_{\rm{CP}}$, and the neutrino mass hierarchy via a joint fit to $\nu_{\mu}$ and $\nu_{e}$ oscillation spectrum. We do this by propagating $\nu_{\mu}$ from the world's most intense neutrino beam at Fermilab, over a baseline of 810 km to northern Minnesota, USA, and measure the $\nu_{\mu}$ to $\nu_{e}$ oscillation probability. NOvA announced its latest oscillation results, based on 8.85$\times10^{20}$ (6.9$\times10^{20}$) protons on target neutrino (antineutrino) data. Preliminary results for the allowed values of oscillation parameters are: $\Delta m^2_{32}=2.51^{+0.12}_{-0.08}\times 10^{-3} \mathrm{eV}^2$, $\mathrm{sin}^2\theta_{23} = 0.58 \pm 0.03$ (upper octant), and $\delta_{\rm{CP}}=0.17\pi$ with preference to the normal hierarchy. Reliable constraints on these oscillation parameters require a rigorous treatment of systematic uncertainties and thorough cross-checks. In this paper, we present an overview of the treatment of systematic uncertainties as well as cross-checks using muon removed simulations and cosmic muon bremsstrahlung showers.