Abstract
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 104 times bigger clusters occur about once a year, then finding time correlations between events in different underground detectors can lead to DM discovery.
Highlights
We will phrase the argument in the context of WIMP searches in the large cryogenic underground experiments the basic statistical arguments are independent of the type of experiments and apply well to searches of axion and other dark matter (DM) particles lighter than conventional WIMPs
Since the cross section of collision with a cluster is σcluster ∼ πR2 we find for the mean free path (MFP) — essentially the distance traveled between collisions is
In this paper we analyse the possible impact of DM clustering at various scales on direct DM searches
Summary
We start with the case of small clusters, defined by having sizes R smaller than the typical linear size L ∼ O(meter) of present DM detectors. Since the kinetic energy of the composites is negligible as compared with their binding, we will view them as effectively elementary WIMPs. When the DM number density in the clusters is less than nuclear density, the DM particles therein scatter incoherently and independently from nuclei in the detectors. When the DM number density in the clusters is less than nuclear density, the DM particles therein scatter incoherently and independently from nuclei in the detectors This is most clearly the case for the dilute large clusters of main interest. The small DM — ordinary matter scattering cross sections exclude any shadowing effects by the different WIMPs in a grain This along with the identical velocity spectra of clustered and unclustered DM suggest that over a very large range formation of both large and small clusters will have no effect on the direct DM searches. The nature of the individual low energy nuclear recoil events in the case of the DM grain would clearly distinguish between the two different cases
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
