Hunting for topological darkmatter with atomic clo

Hunting for topological darkmatter with atomic clocks
A. Derevianko  M. Pospelov 
The cosmological applications of atomic clocks so far have been limited to searches for the uniform-in-time drift of fundamental constants . We point out that a transient-in-time change of fundamental constants can be induced by dark-matter objects that have large spatial extent, such as stable topological defects built fromlightnon-StandardModel fields.
Networks of correlated atomic clocks, some of them already in existence, such as the Global Positioning System, can be used as a powerful tool to search for topological defect dark matter, thus providing another important fundamental physics application for the ever-improving accuracy of atomic clocks.
During the encounter with an extended dark-matter object,  as
it sweeps through the network, initial lysynchronizedclockswill
become desynchronized. Time  discrepancies betweens patially separated clocks are expected to exhibit a distinct signature,encoding the defect’s space structure and its interactionstrength with atoms.
Despite solid evidence for the existence of darkmatter ( 25
the global energy budget in the Universe and 
DM ' 0.3GeVcm
3
in the neighbourhood of the Solar system
7
), its relationship to
particles and fields of the Standard Model (SM) remains a mystery.
Although searches for particle dark matter (DM) are being actively
pursued
8
, there is also significant interest in alternatives, among
which is DM composed from very light fields. Depending on
the initial field configuration at early cosmological times, such
light fields could lead to dark matter via coherent oscillations
around the minimum of their potential, and/or form non-trivial
stable field configurations in physical three-dimensional space if
their potential allows such a possibility. This latter option, which
we will generically refer to as topological defects (TDs), is the
main interest of our paper. The light masses of fields forming the
TDs could lead to a large, indeed macroscopic, size for a defect.
Their encounters with the Earth, combined with the DMSM
coupling, can lead to novel signatures of dark matter expressed
generically in terms of `transient eects'. These eects, coherent
on the scale of individual detectors, are temporary shifts in the
frequencies and phases of measuring devices, rather than large
energy depositions as is the case for microscopic DM. In this
paper we suggest the possibility of a new search technique for
the topological defect dark matter (TDM), based on a network of
atomic clocks.