What antineutrinos can tell about octant and $\delta_{CP}$ in DUNE?

TL;DR

This paper evaluates DUNE's capability to resolve the neutrino oscillation parameters octant of θ23 and δCP, emphasizing the role of antineutrino data in overcoming degeneracies and enhancing sensitivity.

Contribution

It demonstrates how antineutrino runs improve parameter resolution and CP sensitivity in DUNE by exploiting matter effects and degeneracy breaking.

Findings

Antineutrino runs help resolve parameter degeneracies.

Enhanced matter effects increase sensitivity in combined runs.

Antineutrino data improves CP sensitivity by breaking octant-δCP degeneracy.

Abstract

We study the efficiency of DUNE, a next generation long baseline oscillation experiment to resolve two major unknowns in neutrino oscillation physics. These are, octant of $\theta_{23}$ (i.e. if $\theta_{23}$ is $< 45^\circ$ or $>45^\circ$) and Dirac CP phase $\delta_{CP}$. We mainly focus on the role of antineutrinos when they travel 1300 km baseline of DUNE. We observe that for DUNE, the antineutrino runs help to remove parameter degeneracies even in the parameter space where the antineutrino probability suffers from various degeneracies. We study these points in detail and find that, due to enhanced matter effect longer baseline experiments create an increased tension between the neutrino and the antineutrino probabilities which helps to increase total sensitivity in case of combined runs. We also find that, antineutrino run increases overall CP sensitivity due to its ability to abolish octant-$\delta_{CP}$ degeneracy.