Exothermic Dark Matter

Understand

We propose a novel mechanism for dark matter to explain the observed annual modulation signal at DAMA/LIBRA which avoids existing constraints from every other dark matter direct detection experiment including CRESST, CDMS, and XENON10.

• The dark matter consists of at least two light states with mass ~few GeV and splittings ~5 keV.
• It is natural for the heavier states to be cosmologically long-lived and to make up an O(1) fraction of the dark matter.
• Direct detection rates are dominated by the exothermic reactions in which an excited dark matter state down-scatters off of a nucleus, becoming a lower energy state.