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.Read More
arXiv| We perform high-precision calculations of the hyperfine structure for n 2S_1/2 and n 2P_1/2 states of the alkali-metal atoms Rb, Cs, and Fr across principal quantum number n, and studied the trend in the size of the correlations.Read More
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.Read More
We investigate the possibility for the direct detection of low mass (GeV scale) WIMP dark matter in scintillation experiments. Such WIMPs are typically too light to leave appreciable nuclear recoils, but may be detected via their scattering off atomic electrons…Read More
We discuss the theoretical analysis and interpretation of space-time separated clock experiments in the context of a space-time varying scalar field that is non-universally coupled to the standard model fields…Read More
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.Read More
arXiv:1803.00617| Dark matter may induce an asymmetry in the noise distribution of precision measurement devices. A search based on this technique would extend the discovery reach for certain models beyond that of existing experiments by many orders of magnitude.Read More
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.Read More
Invited talk at the Perimeter Institute for Theoretical physics as part of the New Directions in Dark Matter and Neutrino Physics workshop: "Searching for dark matter with GPS and global networks of atomic clocks."Read More
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--
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.