Confidence in a neutrino mass hierarchy determination

Abstract

In the next decade, a number of experiments will attempt to determine the neutrino mass hierarchy. Feasibility studies for such experiments generally determine the statistic Δ χ2. As the hierarchy is a discrete choice, Δχ2 does not obey a one degree of freedom χ2 distribution and so the number of σ's of sensitivity to the hierarchy is not the square root of Δχ2. We present a simple Bayesian formula for the sensitivity to the hierarchy determination that can be expected from the median experiment as a function of Δχ 2. © 2014 SISSA.