The Exposure-Background Duality in the Searches of Neutrinoless Double Beta Decay

TL;DR

This paper analyzes how reducing background noise in neutrinoless double beta decay experiments can significantly lower the required exposure, making the detection of normal mass hierarchy more feasible with realistic resources.

Contribution

It provides a quantitative exploration of the interplay between exposure and background levels, highlighting the importance of background suppression in future experiments.

Findings

Background reduction by 10^{-6} can enable normal hierarchy detection with feasible exposure.

Lower background levels significantly decrease the required target mass and data collection time.

Background suppression is crucial for the next generation of neutrinoless double beta decay experiments.

Abstract

Tremendous efforts are required to scale the summit of observing neutrinoless double beta decay ($0 \nu \beta \beta$). This article quantitatively explores the interplay between exposure (target mass X data taking time) and background levels in $0 \nu \beta \beta$ experiments. In particular, background reduction can substantially alleviate the necessity of unrealistic large exposure as the normal mass hierarchy (NH) is probed. The non-degenerate (ND)-NH can be covered with an exposure of O(100) ton-year, which is only an order of magnitude larger than those planned for next generation projects - provided that the background could be reduced by 0($10^{-6}$) relative to the current best levels. It follows that background suppression will be playing increasingly important and investment-effective, if not determining, roles in future $0 \nu \beta \beta$ experiments with sensitivity goals of approaching and covering ND-NH.