Searching for sterile neutrinos at the ESS$\nu$SB

TL;DR

This paper evaluates the potential of the ESS uSB experiment, with a near detector, to search for sterile neutrinos and control systematic errors in the context of leptonic CP violation studies.

Contribution

It demonstrates that a near detector at about 1 km enhances sensitivity to sterile neutrino oscillations and helps manage systematic uncertainties in the experiment.

Findings

Near detector improves sterile neutrino sensitivity.

Sensitivity to mixing angle down to ~2-8 x 10^{-3}.

Systematic errors significantly impact the detection capability.

Abstract

The ESS$\nu$SB project is a proposed neutrino oscillation experiment based on the European Spallation Source with the search for leptonic CP as its main aim. In this letter we show that a near detector at around 1 km distance from the beamline is not only very desirable for keeping the systematic errors affecting the CP search under control, but would also provide a significant sensitivity probe for sterile neutrino oscillations in the region of the parameter space favored by the long-standing LSND anomaly. We find that the effective mixing angle $\theta_{\mu e}$ can be probed down to $\sin^2(2\theta_{\mu e}) \simeq 2(8)\cdot 10^{-3}$ at $5\sigma$ assuming 15% bin-to-bin (un)correlated systematics.