Implications of CoGeNT’s new results for dark matter

Abstract

The CoGeNT Collaboration has recently presented the results of their first 15 months of data, including the measurement of the spectrum of nuclear recoil candidate events, and the time variation of those events. These results appear consistent with the signal anticipated from a relatively light dark matter particle scattering elastically with nuclei. In this paper, we independently analyze the data set collected by CoGeNT and explore the implications of these results for dark matter. We find that the observed spectrum and rate is consistent with originating from dark matter particles with a mass in the range of 4.5--12 GeV and an elastic scattering cross section with nucleons of approximately $\ensuremath{\sim}{10}^{\ensuremath{-}40}\text{ }\text{ }{\mathrm{cm}}^{2}$. We confirm the conclusion of the CoGeNT Collaboration that the data also includes a somewhat statistically significant ($2.7\ensuremath{\sigma}$) indication of annual modulation, with a phase, period, and amplitude consistent with that predicted for dark matter. CoGeNT's phase is also consistent with the annual modulation reported by the DAMA/LIBRA Collaboration. We also discuss the null results reported by CDMS and XENON100, and comment on the prospects for other experiments to detect a dark matter particle with the properties implied by CoGeNT.