Inelastic Dark Matter at DAMA, CDMS and Future Experiments
David R. Smith, Neal Weiner
TL;DR
Problem: The DAMA annual modulation signal conflicts with CDMS null results under conventional spin-independent WIMP assumptions. Approach: Introduce Inelastic Dark Matter (iDM) with two states $\chi_1$ and $\chi_2$ and a positive mass splitting $\delta$, so scattering is $\chi_1 N \to \chi_2 N$ and requires a velocity threshold $\beta^2 > \frac{2 \delta (m_N+ m_{\chi})}{m_N m_{\chi}}$. Contributions: The paper discusses a SUSY realization as the real component of a sneutrino mixed with a singlet scalar, showing compatibility with experimental constraints and correct relic abundance; it analyzes the modified DAMA signal, noting strong suppression of low-energy events in both modulated and unmodulated components, and discusses future experiments with heavy targets like xenon and tungsten to distinguish iDM. Significance: The iDM framework provides a consistent explanation for DAMA/CDMS and informs experimental design to identify inelastic scattering.
Abstract
The DAMA annual modulation signature, interpreted as evidence for a spin-independent WIMP coupling, seems in conflict with null results from CDMS. However, in models of ``inelastic dark matter'', the experiments are compatible. Inelastic dark matter can arise in supersymmetric theories as the real component of a sneutrino mixed with a singlet scalar. In contrast with ordinary sneutrino dark matter, such particles can satisfy all experimental constraints while giving the appropriate relic abundance. We discuss the modifications to the signal seen at DAMA, in particular noting the strong suppression of low energy events in both modulated and unmodulated components. We discuss future experiments, with emphasis on distinguishing inelastic dark matter from ordinary dark matter, and stressing the significance of experiments with heavy target nuclei, such as xenon and tungsten.