Dark Matter Clusters and Time Correlations in Direct Detection
  Experiments
  Assuming that dark matter (DM) efficiently clusters on various scales we
analyse the possible impact on direct DM searches. For certain sizes and
densities of DM clusters, mutual detector-cluster encounters may occur only
once a year or every several years leading to the apparent failure of
individual experiments searching for DM to discover it. If, however, encounters
with Earth size and up to $10^4$ times bigger clusters occur about once a year,
then finding time correlations between events in different underground
detectors can lead to DM discovery.
