Statistical Tests of Noise and Harmony in Dark Matter Modulation Signals

TL;DR

This paper performs a detailed time-series analysis of dark matter detection data, examining correlations with cosmic ray muons and exploring harmonic signals to better understand the nature of observed modulations.

Contribution

It provides a comprehensive analysis distinguishing dark matter signals from cosmic ray effects and investigates higher harmonics as potential signatures of dark matter.

Findings

No strong correlation between muon flux and dark matter signals.

Different power spectrum and phase between muon flux and dark matter signals.

Higher harmonics, especially biannual, could aid in dark matter detection.

Abstract

The aim of the current work is a detailed time-series analysis of the data from Dark Matter direct detection experiments as well as related datasets. We examine recent claims that the cosmic ray muon flux can be responsible for generating the modulation signals seen by DAMA and, more recently, by the CoGeNT collaboration. We find no evidence for such a strong correlation and show that the two phenomena differ in their power spectrum, phase, and possibly in amplitude. In addition, we investigate in more detail, the time dependence of Dark Matter scattering. Since the signal is periodic with period of a year (due to the Earth's motion around the Sun), the presence of higher harmonics can be expected. We show that the higher harmonics generically have similar phase to the annual modulation and the biannual mode in particular could provide another handle in searching for Dark Matter in the laboratory.