We apply the sum-over-states approach to calculate partial contributions to the parity nonconservation (PNC) in cesium [Porsev et al, Phys. Rev. D 82, 036008 (2010)]. We have found significant corrections to two non-dominating terms coming from the contribution of the core and highly excited states (n > 9, the so called tail). When these differences are taken into account the result of Porsev et al, EPNC = 0.8906 (24) × 10 −11 i(−QW /N ) changes to 0.8977 (40), coming into good agreement with our previous calculations, 0.8980 (45). The interpretation of the PNC measurements in cesium still indicates reasonable agreement with the standard model (1.5 σ), however gives new constraints on physics beyond it.

Cosmological observations indicate that dark matter makes up 85% of all matter in the universe yet its microscopic composition remains a mystery. Dark matter could arise from ultralight quantum fields that form macroscopic objects. Here we use the global positioning system as a ~ 50,000 km aperture dark matter detector to search for such objects in the form of domain walls. Global positioning system navigation relies on precision timing signals furnished by atomic clocks. As the Earth moves through the galactic dark matter halo, interactions with domain walls could cause a sequence of atomic clock perturbations that propagate through the satellite constellation at galactic velocities ~ 300 km s−1. Mining 16 years of archival data, we find no evidence for domain walls at our current sensitivity level. This improves the limits on certain quadratic scalar couplings of domain wall dark matter to standard model particles by several orders of magnitude.

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. Recent developments in both atomic theory and experimental methods have led to the ability to make extremely precise theoretical calculations and experimental measurements of these effects. Such studies are complementary to direct high-energy searches, and can be performed for just a fraction of the cost. We review the recent progress in the field of parity and time-reversal violation in atoms, molecules, and nuclei, and examine the implications for physics beyond the Standard Model, with an emphasis on possible areas for development in the near future.

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. Unlike the WIMPnucleon scattering, where current experiments probe typical interaction strengths much smaller than the Fermi constant, the scattering on electrons requires a much stronger interaction to be detectable, which in turn requires new light force carriers. We account for such new forces explicitly, by introducing a mediator particle with scalar or vector couplings to dark matter and to electrons. We then perform state of the art numerical calculations of atomic ionization relevant to the existing experiments. Our goals are to consistently take into account the atomic physics aspect of the problem (e.g., the relativistic effects, which can be quite significant), and to scan the parameter space: the dark matter mass, the mediator mass, and the effective coupling strength, to see if there is any part of the parameter space that could potentially explain the DAMA modulation signal. 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.

We propose methods for extracting limits on the strength of P-odd interactions of pseudoscalar and pseudovector cosmic fields with electrons, protons and neutrons. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by standard-model extensions. Calculations of parity nonconserving amplitudes and atomic electric dipole moments induced by these fields are performed for H, Li, Na, K, Rb, Cs, Ba + , Tl, Dy, Fr, and Ra + . From these calculations and existing measurements in Dy, Cs and Tl, we constrain the interaction strengths of the parity-violating static pseudovector cosmic field to be 7 × 10 −15 GeV with an electron, and 3 × 10 −8 GeV with a proton.

Parity nonconservation amplitudes are calculated for the 7s-6d 3/2 transitions of the francium isoelectronic sequence (Fr, Ra + , Ac 2+ , Th 3+ , Pa 4+ , U 5+ and Np 6+ ) and for the 6s-5d 3/2 transitions of the cesium isoelectronic sequence (Cs, Ba + , La 2+ , Ce 3+ and Pr 4+ ). We show in particular that isotopes of La 2+ , Ac 2+ and Th 3+ ions have strong potential in the search for new physics beyond the standard model -the PNC amplitudes are large, the calculations are accurate and the nuclei are practically stable. In addition, 232 Th 3+ ions have recently been trapped and cooled [C. J. Campbell et al., Phys. Rev. Lett. 102, 233004 (2009)]. We also extend previous works by calculating the s-s PNC transitions in Ra + and Ba + , and provide new calculations of several energy levels, and electric dipole and quadrupole transition amplitudes for the Fr-like actinide ions.

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. The results are used to constrain important fundamental parameters describing the strength of the interaction of various cosmic fields with electrons, protons, and neutrons. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by standard-model extensions.Calculations of the effects induced by pseudoscalar and pseudovector fields are performed for . Existing parity nonconservation experiments in Cs, Dy, Yb, and Tl are combined with these calculations to directly place limits on the interaction strength between the temporal component, b0, of a static pseudovector cosmic field and the atomic electrons, with the most stringent limit of |b e 0 | < 7 × 10 −15 GeV, in the laboratory frame of reference, coming from Dy. From a measurement of the nuclear anapole moment of Cs, and a limit on its value for Tl, we also extract limits on the interaction strength between the temporal component of this cosmic field, as well as a related tensor cosmic-field component d00, with protons and neutrons. The most stringent limits of |b p 0 | < 4 × 10 −8 GeV and |d p 00 | < 5 × 10 −8 for protons, and |b n 0 | < 2 × 10 −7 GeV and |d n 00 | < 2 × 10 −7 for neutrons (in the laboratory frame) come from the results using Cs. Axions may induce oscillating parity-and time-reversal-violating effects in atoms and molecules through the generation of oscillating nuclear magnetic quadrupole and Schiff moments, which arise from P -and T -odd intranuclear forces and from the electric dipole moments of constituent nucleons. Nuclear-spin-independent parity nonconservation effects may be enhanced in diatomic molecules possessing close pairs of opposite-parity levels in the presence of time-dependent interactions.

We search for transient variations of the fine structure constant using data from a European network of fiber-linked optical atomic clocks. By searching for coherent variations in the recorded clock frequency comparisons across the network, we significantly improve the constraints on transient variations of the fine structure constant. For example, we constrain the variation to |δα/α| < 5 × 10−17 for transients of duration 103 s. 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. At the current sensitivity level, we find no evidence for dark matter in the form of topological defects (or, more generally, any macroscopic objects), and we thus place constraints on certain potential couplings between the dark matter and standard model particles, substantially improving upon the existing constraints, particularly for large (≳104 km) objects.