Physics Potential of ESS$\nu$SB in the presence of a Light Sterile Neutrino

TL;DR

This study evaluates the ESS$ u$SB neutrino experiment's ability to detect CP violation and other neutrino properties, especially considering the presence of a light sterile neutrino, revealing limitations and sensitivities in different scenarios.

Contribution

It provides a detailed analysis of ESS$ u$SB's performance in 3$ u$ and 3+1 neutrino schemes, highlighting the impact of sterile neutrinos on CP violation sensitivity.

Findings

CPV sensitivity decreases from 3$ u$ to 4$ u$ scenario.

Phases $ heta_{13}$ and $ heta_{14}$ can be reconstructed with uncertainties of ~15° and ~35°.

Poor sensitivity to $ heta_{23}$ octant in both schemes.

Abstract

ESS$\nu$SB is a proposed neutrino super-beam project at the ESS facility. We study the performance of this setup in the presence of a light eV-scale sterile neutrino, considering 540 km baseline with 2 years (8 years) of $\nu$ ($\bar\nu$) run-plan. This baseline offers the possibility to work around the second oscillation maximum, providing high sensitivity towards CP-violation (CPV). We explore in detail its capability in resolving CPV generated by the standard CP phase $\delta_{13}$, the new CP phase $\delta_{14}$, and the octant of $\theta_{23}$. We find that the sensitivity to CPV induced by $\delta_{13}$ deteriorates noticeably when going from $3\nu$ to 4$\nu$ case. The two phases $\delta_{13}$ and $\delta_{14}$ can be reconstructed with a 1$\sigma$ uncertainty of $\sim15^0$ and $ \sim35^0$ respectively. Concerning the octant of $\theta_{23}$, we find poor sensitivity in both $3\nu$ and $4\nu$ schemes. Our results show that a setup like ESS$\nu$SB working around the second oscillation maximum with a baseline of 540 km, performs quite well to explore CPV in 3$\nu$ scheme, but it is not optimal for studying CP properties in 3+1 scheme.