A Spin-Dependent Interpretation for Possible Signals of Light Dark Matter

TL;DR

This paper explores a spin-dependent interaction model for light dark matter signals, showing compatibility with multiple experiments but also highlighting ongoing conflicts with null results from other detectors.

Contribution

It introduces a spin-dependent neutron interaction framework that can reconcile signals from CoGeNT and CDMS-II silicon with existing null results, expanding the interpretation of light dark matter signals.

Findings

CoGeNT and CDMS-II silicon signals are compatible with spin-dependent neutron interactions.

Tension remains with xenon-based null results like XENON100 and XENON10.

Combining spin-dependent interactions with both protons and neutrons increases experimental conflicts.

Abstract

Signals broadly compatible with light (7-10 GeV) dark matter have been reported in three direct detection experiments: CoGeNT, DAMA/LIBRA, and CDMS-II silicon. These possible signals have been interpreted in the context of spin-independent interactions between the target nuclei and dark matter, although there is tension with null results, particularly from xenon-based experiments. In this paper, we demonstrate that the CoGeNT and CDMS-II silicon results are also compatible assuming a spin-dependent neutron interaction, though this is in tension with xenon-based experiments and PICASSO. The tension with the null results from XENON100 and XENON10 is approximately the same as for the spin-independent coupling. All three experimental signals can be made compatible through a combination of spin-dependent interactions with both the proton and neutron, although such a scenario increases the conflict with the null results of other experiments.