Implications of CoGeNT and DAMA for light WIMP dark matter

Abstract

In this paper, we study the recent excess of low energy events observed by the CoGeNT Collaboration, and discuss the possibility that these events originate from the elastic scattering of a light (${m}_{\mathrm{DM}}\ensuremath{\sim}5--10\text{ }\text{ }\mathrm{GeV}$) weakly interacting massive particle (WIMP). We find that such a dark matter candidate may also be capable of generating the annual modulation reported by DAMA, without conflicting with the null results from other experiments, such as XENON10. The regions implied by CoGeNT and DAMA are also near those required to produce the two observed CDMS events. A dark matter interpretation of the CoGeNT and DAMA observations favors a region of parameter space that is especially attractive within the context of asymmetric dark matter models. In such models, the cosmological dark matter density arises from the baryon asymmetry of the Universe, naturally leading to the expectation that ${m}_{\mathrm{DM}}\ensuremath{\sim}1--10\text{ }\text{ }\mathrm{GeV}$. We also discuss neutralino dark matter from extended supersymmetric frameworks, such as the next-to-minimal supersymmetric standard model. Lastly, we explore the implications of such a dark matter candidate for indirect searches, and find very encouraging prospects for experiments attempting to detect neutrino or gamma ray annihilation products.