Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks

arXiv| We search for transient variations of the fine structure constant using data from a European network of fiber-linked optical atomic clocks. This analysis also presents a possibility to search for dark matter, the mysterious substance hypothesised to explain galaxy dynamics and other astrophysical phenomena that is thought to dominate the matter density of the universe.

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Calculations of the atomic structure for the low-lying states of actinium

Phys.Rev.A| We employ a technique that combines the configuration interaction method with the singles-doubles coupled-cluster method to perform calculation of the energy levels, transition amplitudes, lifetimes, g-factors, and magnetic dipole and electric quadrupole hyperfine structure constants for many low-lying states of neutral actinium.

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Search for transient ultralight dark matter signatures with networks of precision measurement devices using a Bayesian statistics method

Phys. Rev. D| By analyzing the satellite and terrestrial atomic clock data, it is possible to search for transient signatures of exotic physics, such as "clumpy" dark matter and dark energy, effectively transforming the GPS constellation into a 50,000 km aperture sensor array. 

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Search for domain wall dark matter with atomic clocks on board global positioning system satellites

Nature Communications (open access):  Mining 16 years of archival GPS data, we find no evidence for DM clumps in the form of domain walls. This enables us to improve limits on DM couplings to atomic clocks by several orders of magnitude. Our work demonstrates the use of a global network of precision measurement devices in the search for DM.

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Astrophysicists Turn GPS Satellite Constellation into Giant Dark Matter Detector

The MIT Technology Review featured an article on some of our recent work:
Astrophysicists Turn GPS Satellite Constellation into Giant Dark Matter Detector. If Earth is sweeping through an ocean of dark matter, the effects should be visible in clock data from GPS satellites....
--See the whole article at MIT Technology Review--

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Dark matter scattering on electrons: Accurate calculations of atomic excitations and implications for the DAMA signal

Phys. Rev. D We revisit the WIMP-type dark matter scattering on electrons that results in atomic ionization, and can manifest itself in a variety of existing direct-detection experiments.
While we find that the modulation fraction of all events with energy deposition above 2 keV in NaI can be quite significant, reaching ~50%, the relevant parts of the parameter space are excluded by the XENON10 and XENON100 experiments.

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