Neutrinoless Double Beta Decay, the Inverted Hierarchy and Precision Determination of theta(12)

Understand

Ruling out the inverted neutrino hierarchy with neutrinoless double beta decay experiments is possible if a limit on the effective mass below the minimal theoretically possible value is reached.

• We stress that this lower limit depends strongly on the value of the solar neutrino mixing angle: it introduces an uncertainty of a factor of 2 within its current 3 sigma range.
• If an experiment is not background-free, a factor of two in effective mass corresponds to a combined factor of 16 improvement for the experimental parameters running time, detector mass, background level and energy resolution.
• Therefore, a more precise determination of theta(12) is crucial for the interpretation of experimental results and the evaluation of the potential and requirements for future experiments.