Casting a Wide Signal Net with Future Direct Dark Matter Detection Experiments

TL;DR

This paper investigates how various neutrino backgrounds impact the detection of diverse dark matter interactions in future experiments, highlighting strategies to overcome the neutrino floor and improve discovery potential.

Contribution

It explores the effects of neutrino backgrounds on a broad range of dark matter models and identifies conditions where neutrino interference can be mitigated or lifted.

Findings

Neutrino backgrounds do not suppress detection for certain momentum-suppressed cross sections.

Inelastic scattering can help distinguish dark matter signals from neutrino backgrounds.

Heavy targets and large dark matter masses can reduce neutrino background effects.

Abstract

As dark matter (DM) direct detection experiments continue to improve their sensitivity they will inevitably encounter an irreducible background arising from coherent neutrino scattering. This so-called "neutrino floor" may significantly reduce the sensitivity of an experiment to DM-nuclei interactions, particularly if the recoil spectrum of the neutrino background is approximately degenerate with the DM signal. This occurs for the conventionally considered spin-independent (SI) or spin-dependent (SD) interactions. In such case, an increase in the experiment's exposure by multiple orders of magnitude may not yield any significant increase in sensitivity. The typically considered SI and SD interactions, however, do not adequately reflect the whole landscape of the well-motivated DM models, which includes other interactions. Since particle DM has not been detected yet in laboratories, it is essential to understand and maximize the detection capabilities for a broad variety of possible models and signatures. In this work we explore the impact of the background arising from various neutrino sources on the discovery potential of a DM signal for a large class of viable DM-nucleus interactions and several potential futuristic experimental settings, with different target elements. For some momentum suppressed cross sections, large DM particle masses and heavier targets, we find that there is no suppression of the discovery limits due to neutrino backgrounds. Further, we explicitly demonstrate that inelastic scattering, which could appear in models with multicomponent dark sectors, would help to lift the signal degeneracy associated with the neutrino floor. This study could assist with mapping out the optimal DM detection strategy for the next generation of experiments.