Spin-independent elastic WIMP scattering and the DAMA annual modulation signal

TL;DR

This paper analyzes the DAMA annual modulation signal in terms of spin-independent elastic WIMP scattering, concluding that the signal is incompatible with other experiments under realistic dark matter halo assumptions.

Contribution

It provides a comprehensive analysis including channeling effects and realistic halo models, showing the DAMA signal cannot be explained by low-mass WIMPs consistent with other constraints.

Findings

DAMA signal favors WIMP masses near 12 GeV

No overlap with CDMS/XENON constraints at 90% CL

Extreme halo assumptions are needed for compatibility

Abstract

We discuss the interpretation of the annual modulation signal seen in the DAMA experiment in terms of spin-independent elastic WIMP scattering. Taking into account channeling in the crystal as well as the spectral signature of the modulation signal we find that the low-mass WIMP region consistent with DAMA data is confined to WIMP masses close to $m_\chi \simeq 12$ GeV, in disagreement with the constraints from CDMS and XENON. We conclude that even if channeling is taken into account this interpretation of the DAMA modulation signal is disfavoured. There are no overlap regions in the parameter space at 90% CL and a consistency test gives the probability of $1.2\times 10^{-5}$. We study the robustness of this result with respect to variations of the WIMP velocity distribution in our galaxy, by changing various parameters of the distribution function, and by using the results of a realistic N-body dark matter simulation. We find that only by making rather extreme assumptions regarding halo properties can we obtain agreement between DAMA and CDMS/XENON.