Magical properties of 2540 Km baseline Superbeam Experiment

TL;DR

This paper proposes a 2540 km baseline superbeam experiment that can determine neutrino mass hierarchy independently of the CP phase using a narrow band neutrino beam peaking at 3.5 GeV, requiring modest exposure times.

Contribution

It introduces the concept of a 2540 km baseline as a 'magical' distance for neutrino experiments, enabling hierarchy determination without CP phase dependence.

Findings

Hierarchy can be determined independently of CP phase at 2540 km.

Modest exposure times are sufficient for certain mixing angles.

The approach overcomes flux generation challenges at very long baselines.

Abstract

Lack of any information on the CP violating phase $\dcp$ weakens our ability to determine neutrino mass hierarchy. Magic baseline of 7500 km was proposed to overcome this problem. However, to obtain large enough fluxes, at this very long baseline, one needs new techniques of generating high intensity neutrino beams. In this letter, we highlight the {\it magical} properties of a 2540 km baseline. At such a baseline, using a narrow band neutrino superbeam whose flux peaks around the energy 3.5 GeV, we can determine neutrino mass hierarchy {\bf independent} of the CP phase. For $\sin^2 2 \theta_{13} \geq 0.05$, a very modest exposure of 10 Kiloton-years is sufficient to determine the hierarchy. For $0.02 \leq \sin^2 2 \theta_{13} \leq 0.05$, an exposure of about 100 Kiloton-years is needed.