Abstract
Three dark matter direct detection experiments (DAMA/LIBRA, CoGeNT, and
CRESST-II) have each reported signals which are not consistent with known
backgrounds, but resemble that predicted for a dark matter particle with a mass
of roughly $\sim$10 GeV and an elastic scattering cross section with nucleons
of $\sim$$10^{-41}$--$10^{-40}$ cm$^2$. In this article, we compare the signals
of these experiments and discuss whether they can be explained by a single
species of dark matter particle, without conflicting with the constraints of
other experiments. We find that the spectrum of events reported by CoGeNT and
CRESST-II are consistent with each other and with the constraints from CDMS-II,
although some tension with xenon-based experiments remains. Similarly, the
modulation signals reported by DAMA/LIBRA and CoGeNT appear to be compatible,
although the corresponding amplitude of the observed modulations are a factor
of at least a few higher than would be naively expected, based on the event
spectra reported by CoGeNT and CRESST-II. This apparent discrepancy could
potentially be resolved if tidal streams or other non-Maxwellian structures are
present in the local distribution of dark matter.