Exposure-background duality in the searches of neutrinoless double beta decay

Abstract

Neutrinoless double-β decay (0υββ) is an experimentally sensitive avenue to probe the nature (Majorana versus Dirac) and exact mass of neutrinos. This work quantitatively explores the interplay between exposure and background levels in 0υββ experiments at their design stage. Although the primary goal of current running and projected experiments is to probe the inverted mass hierarchy, current neutrino oscillation experiments reveal a preference for non-degenerate (ND) normal mass hierarchy. Therefore the strategy of scaling the summit of 0υββ should also take this genuine possibility into account. Present work would explore the role of background suppression in alleviating the necessity of large exposure for future 0υββ experiments with sensitivity goals of approaching and covering ND-NH. In particular, the roles of energy resolution in suppressing the irreducible background of 2υββ are investigated.