Probing Neutrino Oscillation Parameters using High Power Superbeam from ESS

TL;DR

This study evaluates the physics potential of a high-power superbeam experiment at ESS, focusing on CP violation, atmospheric parameters, and theta23 octant, with optimal baselines and run plans identified for different goals.

Contribution

It provides a comparative analysis of baseline choices and run configurations for maximizing sensitivity to CP violation and theta23 octant at ESS.

Findings

540 km baseline with 7nu+3nubar run-plan offers best CP violation sensitivity.

200 km baseline performs better for non-maximal theta23 and octant determination.

5sigma CP violation detection possible for 48% of deltaCP values with optimal setup.

Abstract

A high-power neutrino superbeam experiment at the ESS facility has been proposed such that the source-detector distance falls at the second oscillation maximum, giving very good sensitivity towards establishing CP violation. In this work, we explore the comparative physics reach of the experiment in terms of leptonic CP-violation, precision on atmospheric parameters, non-maximal theta23, and its octant for a variety of choices for the baselines. We also vary the neutrino vs. the anti-neutrino running time for the beam, and study its impact on the physics goals of the experiment. We find that for the determination of CP violation, 540 km baseline with 7 years of neutrino and 3 years of anti-neutrino (7nu+3nubar) run-plan performs the best and one expects a 5sigma sensitivity to CP violation for 48% of true values of deltaCP. The projected reach for the 200 km baseline with 7nu+3nubar run-plan is somewhat worse with 5sigma sensitivity for 34% of true values of deltaCP. On the other hand, for the discovery of a non-maximal theta23 and its octant, the 200 km baseline option with 7nu+3nubar run-plan performs significantly better than the other baselines. A 5sigma determination of a non-maximal theta23 can be made if the true value of sin^2theta23 lesssim 0.45 or sin^2theta23 gtrsim 0.57. The octant of theta23 could be resolved at 5sigma if the true value of sin^2theta23 lesssim 0.43 or gtrsim 0.59, irrespective of deltaCP.