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

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 $\sim 15^0$ and $\sim 35^0$ 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.

Comments: minor changes in text; added references; version accepted for publication in JHEP