DAMA and WIMP dark matter

TL;DR

The paper investigates whether conventional WIMPs with spin-independent interactions can explain DAMA's annual modulation while remaining compatible with null results from other detectors. It develops a standard direct-detection formalism with a Maxwell-Boltzmann halo, channeling effects in DAMA, and both elastic and inelastic scattering scenarios, and applies a 90% CL constraint framework across multiple experiments. The authors find a viable light-WIMP region with m_DM ≈ 3–8 GeV and σ_p ≈ 3×10^−41–5×10^−39 cm^2 that reconciles DAMA with CDMS, CRESST, and XENON when channeling is included; inelastic channels offer little extra space. They predict that upcoming low-threshold detectors, such as CDMSII-Si and ultra-low-energy Ge detectors, will probe this parameter region.

Abstract

We study whether spin-independent scattering of weakly-interacting massive particles (WIMPs) with nuclei can account for the annual modulation signal reported by DAMA. We consider both elastic and inelastic scattering processes. We find that there is a region of WIMP parameter space which can simultaneously accommodate DAMA and the null results of CDMS, CRESST, and XENON. This region corresponds to an ordinary, elastically-scattering WIMP with a standard Maxwell-Boltzmann distribution, a mass 3 GeV < m_{DM} <8 GeV, and a spin-independent cross section with nucleons 3 \times 10^{-41} cm^2 < σ_p^{SI} < 5 \times 10^{-39} cm^2. This new region of parameter space depends crucially on the recently discovered effect of channeling on the energy threshold for WIMP detection in the DAMA experiment; without the inclusion of this effect, the DAMA allowed region is essentially closed by null experiments. Such low-mass WIMPs arise in many theories of Beyond the Standard Model physics, from minimal extensions of the MSSM to solutions of the baryon-dark matter coincidence problem. We find that inelastic scattering channels do not open up a significant parameter region consistent with all experimental results. Future experiments with low energy thresholds for detecting nuclear recoils, such as CDMSII-Si and those utilizing ultra-low energy germanium detectors, will be able to probe the DAMA region of parameter space.