My research focuses on tests of fundamental theories and searches for dark matter. Currently a postdoctoral scholar at the University of Queensland, Australia, working in theoretical atomic physics and particle astrophysics. Previously at SYRTE, the Observatoire de Paris, France, working on possibilities for dark matter detection using high-precision atomic clocks, and the University of Nevada, Reno, as part of the GPS.DM Collaboration. I completed my PhD in theoretical atomic physics in 2016 at UNSW, Australia, in Sydney.

## Recent research & publications:

**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.

**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.

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…

Conferences, workshops, and invited talks in 2019

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…

Conferences, workshops, and invited talks in 2018

**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.

**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.

**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.

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."

Conferences, workshops, and invited talks in 2017

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--

Science Magazine did a short write-up of some of our recent work: *A team of physicists has used data from GPS satellites to hunt for dark matter...*

--Continue Reading at sciencemag.org--

**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.

A huge effort from scientists all around the world has pushed tests of physics to ever higher energy scales (e.g. at CERN), though no trace of non-standard model physics has yet been found. In this thesis, I explore another avenue: the use of high precision atomic physics to study fundamental interactions at low energy.

**Phys. Rev. Lett. **Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 sigma annual modulation in the DAMA dark matter direct detection experiment. We also show that electron relativistic effects actually give the dominant contribution to such a process, meaning that nonrelativistic calculations may greatly underestimate the cross section.

**Ann. Rev. Nuc. Part. Sci.:** Studying the violation of parity and time-reversal invariance in atomic systems has proven to be a very effective means for testing the electroweak theory at low energy and searching for physics beyond it. We review the recent progress in the field of parity and time-reversal violation in atoms, molecules, and nuclei

**Phys. Rev. D. **We propose methods and present calculations that can be used to search for evidence of cosmic fields by investigating the parity-violating effects, including parity nonconservation amplitudes and electric dipole moments, that they induce in atoms.

**Phys. Rev. D** We derive the relativistic factor for splitting of the *g*-factors of a fermion and its anti-fermion partner, which is important for placing constraints on dimension-five, *CPT*-odd and Lorentz-invariance-violating interactions from experiments performed in a cyclotron. From existing data, we extract limits (1σ) on the coupling strengths..

**Phys. Rev. Lett.** We propose methods for extracting limits on the strength of *P*-odd interactions of pseudoscalar and pseudovector cosmic fields with electrons, protons and neutrons, by exploiting the static and dynamic parity-nonconserving amplitudes and electric dipole moments they induce in atoms. Candidates for such fields are dark matter (including axions)..

**Phys. Rev. A** We present calculations of nuclear-spin-dependent and nuclear-spin-independent parity violating amplitudes in Ba, Ra, Ac+, Th and Pa. Parity nonconservation in these systems is greatly enhanced due to the presence of very close electronic energy levels of opposite parity, large nuclear charge, and strong nuclear enhancement of parity-violating effects.

**Phys. Rev. A** We perform calculations of s-d_5/2 nuclear-spin-dependent parity nonconservation amplitudes for Rb, Cs, Ba+, Yb+, Fr, Ra+ and Ac2+...

**Phys. Rev. A** We present a detailed study of the effect of double core polarization for amplitudes of the *ss* and *sd* parity-nonconserving transitions...

**Phys. Rev. A** Parity nonconservation amplitudes are calculated for the 7s - 6d_3/2 transitions of the francium isoelectronic sequence..

**Phys. Rev. A** We use the radiative potential method to calculate QED corrections to energy levels and dipole amplitudes. In conjunction with the existing weak amplitude calculations, this provides the QED corrections to the PNC amplitudes for several atoms of interest to parity nonconservation calculations...

**Phys. Rev. A** We calculate the PNC 5s - 6s electric dipole transition amplitude in rubidium and demonstrate that rubidium is a good candidate to search for new physics beyond the standard model since accuracy of the atomic calculations in rubidium can be higher than in cesium...

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.