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