2010/04/30 by Peter W. Graham, Roni Harnik, Surjeet Rajendran +1
Physics and Astronomy · #Astrophysics #Atomic physics #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark energy #Dark matter #Excited state #Exothermic reaction #Light dark matter #Particle physics #Particle physics theoretical and experimental studies #Physics #Scalar field dark matter #Warm dark matter #astro-ph.CO #astro-ph.HE #hep-ex #hep-ph
paper · pdf · doi:10.1103/physrevd.82.063512
published as Phys.Rev.D82:063512,2010 · 29 pages, 7 figures, minor updates and references added, version accepted by PRD
openalex publication_date 2010/09/09 · arxiv created 2010/10/06 · arxiv updated 2010/10/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 \ensuremath∼few GeV and splittings \ensuremath∼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 downscatters off of a nucleus, becoming a lower energy state. In contrast to (endothermic) inelastic dark matter, the most sensitive experiments for exothermic dark matter are those with light nuclei and low threshold energies. Interestingly, this model can also naturally account for the observed low-energy events at CoGeNT. The only significant constraint on the model arises from the DAMA/LIBRA unmodulated spectrum but it can be tested in the near future by a low-threshold analysis of CDMS-Si and possibly other experiments including CRESST, COUPP, and XENON100.