An optimistic CoGeNT analysis

TL;DR

This paper analyzes light dark matter models, including millicharged atomic dark matter, in relation to CoGeNT and other experimental data, finding inelastic models fit better but face challenges explaining DAMA results.

Contribution

It introduces an analysis of MADM and other light dark matter models fitting CoGeNT data while considering experimental constraints and background effects.

Findings

Inelastic magnetic dark matter provides the best fit to data.

Including tidal debris improves model fits and reduces tension with constraints.

MADM can fit CoGeNT data but struggles to explain DAMA results.

Abstract

Inspired by a recently proposed model of millicharged atomic dark matter (MADM), we analyze several classes of light dark matter models with respect to CoGeNT modulated and unmodulated data, and constraints from CDMS, XENON10 and XENON100. After removing the surface contaminated events from the original CoGeNT data set, we find an acceptable fit to all these data (but with the modulating part of the signal making a statistically small contribution), using somewhat relaxed assumptions about the response of the null experiments at low recoil energies, and postulating an unknown modulating background in the CoGeNT data at recoil energies above 1.5 keVee. We compare the fits of MADM---an example of inelastic magnetic dark matter---to those of standard elastically and inelastically scattering light WIMPs (eDM and iDM). The iDM model gives the best fit, with MADM close behind. The dark matter interpretation of the DAMA annual modulation cannot be made compatible with these results however. We find that the inclusion of a tidal debris component in the dark matter phase space distribution improves the fits or helps to relieve tension with XENON constraints.