### Conveners

#### Variation of the Fundamental Constants, Tests of the Fundamental Symmetries and Probes of the Dark Sector: Block 1

- Yevgeny Stadnik ()
- Victor Flambaum (University of New South Wales, School of Physics, Sydney 2052, Australia)

#### Variation of the Fundamental Constants, Tests of the Fundamental Symmetries and Probes of the Dark Sector: Block 2

- Yevgeny Stadnik ()
- Victor Flambaum (University of New South Wales, School of Physics, Sydney 2052, Australia)

#### Variation of the Fundamental Constants, Tests of the Fundamental Symmetries and Probes of the Dark Sector: Block 3

- Yevgeny Stadnik ()
- Victor Flambaum (University of New South Wales, School of Physics, Sydney 2052, Australia)

### Description

This session is devoted to recent developments in the investigation of and high-precision searches for variations of the fundamental constants of nature and tests of the fundamental symmetries of nature, including application to searches for ultra-low-mass dark matter and related dark components, as well as dark forces.

The isotope shifts (IS) in the frequency of an atomic transition are approximately linearly correlated with the shifts in another transition. This linearity is reflected in the so-called King-plot analysis. It has been suggested to search for deviations from linearity as a way to probe beyond-Standard-Model interactions mediated by light bosons [1]. These searches require availability of...

In this talk I want to discuss the (unorthodox) scenario when the baryogenesis is replaced by a charge segregation process in which the global baryon number of the Universe remains zero. In this, the so-called axion quark nugget (AQN) dark matter model the unobserved antibaryons come to comprise the dark matter in the form of dense nuggets. In this framework, both types of matter (dark and...

We report on our progress of an improved test of local Lorentz invariance (LLI) in the electron-photon sector using the highly sensitive meta-stable electronic $F$-state of the $^{172}$Yb$^{+}$ ion [1].

The Zeeman structure of the $F$-state contains two orthogonally oriented orbitals which gives us access to test LLI violation. To suppress the magnetic field noise during the measurement,...

In this talk, I will present some recent results on estimating the performance of quantum optomechanical sensors for searches of modified gravity. Specifically, I will show how we derive the best possible bounds that can be placed on Yukawa- and chameleon-like modifications to the Newtonian gravitational potential with a cavity optomechanical quantum sensor. We do so by modelling the effects...

The primordial abundance of lithium is still a subject of controversy, given the disagreement between numerical results and observational estimates. We show how this discrepancy can be undestood in the context of variation of fundamental constants at the epoch of Big Bang Nucleosynthesis. The variation of Newton's constant plays a crucial role. In particular, its interpretation in terms of...

Revolutionary progress is underway in the ability to detect CP-violating electric dipole moments (EDMs) of particles such as the electron and proton. I will describe recent searches for the electron EDM that are already sensitive to new physics at scales around 10 TeV. I will also discuss new techniques projected to soon enable orders of magnitude further improvement in the field.

Interaction between the standard model matter and low mass scalar dark matter field may be presented as variation of the fundamental constant while interaction with an axion-like field leads to oscillating effects of violation of the fundamental symmetries including electric dipole moments. New interactions mediated by hypothetical particles produce effects, which may be observed in atomic...

In this work we present our latest results using photonic, atomic, and mechanical oscillators to undertake experimental searches for dark matter and tests of fundamental physics. First, we will focus on our recent results on searching for scalar dark matter through frequency comparisons, due to oscillations in fundamental constants [1]. Next we will discuss upconverting low mass axion signals...

The hypothetical variation of the fine structure constant alpha can be studied in a laboratory by comparing two exceptionally accurate atomic clocks over a long period of time. It is especially convenient when the two clock transitions, sensitive to the variation of alpha are found in the same atom. We identify two such systems, the neutral ytterbium and gold atoms. The Yb I atom has at least...

A clock in a higher place ticks faster than one in a lower place in accordance with Einstein’s general relativity. A pair of atomic clocks serve as a quantum sensor for the gravitational potential. The relativistic effects of the 450-meter height difference of a broadcasting tower, Tokyo Skytree, were measured using a pair of optical lattice clocks to verify the general theory of relativity....

The observational evidence for the recent acceleration of the universe shows that canonical theories of cosmology and particle physics are incomplete and that new physics is out there, waiting to be discovered. A compelling task for astrophysical facilities is to search for, identify and ultimately characterize this new physics. I will present very recent developments in tests of the stability...

The Standard Model of particle physics is both incredibly successful and glaringly incomplete. Among the questions left open is the striking imbalance of matter and antimatter in our universe, which inspires experiments to compare the fundamental properties of matter/antimatter conjugates with high precision. The BASE collaboration at the antiproton decelerator of CERN is performing such...

We point out that in models of macroscopic topological defects composed of one or more scalar fields that interact with standard-model fields via scalar-type couplings, the back-action of ambient matter on the scalar field(s) produces an environmental dependence of the fundamental constants of nature, as well as spatial variations of the fundamental constants in the vicinity of dense bodies...

The extraordinary advances in quantum control of matter and light have been transformative for precision measurements enabling probes of the most basic laws of Nature to gain fundamental understanding of the physical Universe. The development of atomic clocks with systematic uncertainties in the 10$^{-18}$ range enables searches for the variation of fundamental constants, dark matter, and...

Searches for violations of Einstein’s equivalence principle, such as tests of local Lorentz invariance and local position invariance, have become one of the leading applications of low-energy, high-precision experiments with laser-cooled atoms. In our laboratory, we operate atomic clocks based on the microwave ground state hyperfine splitting frequency of Caesium and optical clocks based on...

We report on the first direct search for low-mass scalar field dark matter utilising a gravitational-wave detector. We set new upper limits for the coupling constants of scalar field dark matter as a function of its mass by excluding the presence of signals that would be produced through the direct coupling of this dark matter to the beamsplitter of the GEO600 interferometer. The new...

Precision measurements of isotope shifts could reveal new physics beyond the Standard Model. Measurements of these shifts for two transitions in at least three pairs of isotopes for a given element allows the construction of a so-called King plot, where deviations from linear behaviour could point to a previously unknown boson mediating a fifth fundamental force that couples electrons to...

To avoid ambiguity in the phase readout, optical clock measurements are constrained to operate with an interrogation time that is short enough that the accumulated optical local oscillator (OLO) phase wander remains within ±π/2 radians. This constraint, known as the coherence limit, has motivated a variety of techniques to allow interrogations beyond this limit. A recent proposal has been put...