DARK MAtter for Precision experiments (DARKMAP) Renewal

Our best understanding of the inner working of the Universe demands that Dark Matter contributes about 80% of the total mass of the Universe, shaping its form at all astronomical scales. However, the composition of Dark Matter in terms of fundamental particles remains a puzzle and all attempts to solve it through measurements or direct observation have failed to date.

Established experiments have focussed on searches for Dark Matter that scatters off heavy atoms in deep underground labs, assuming it behaves like slowly moving particles. This type of Dark Matter is called Weakly Interacting Massive Particle (WIMP) and its mass is a multiple of the proton mass.

For Dark Matter masses below the mass of a Carbon atom the momentum of the slowly moving WIMPs drops below the recoil threshold of the heavy nuclei used in these experiments and it cannot be detected anymore.

If Dark Matter is much lighter, its properties are fundamentally different, and it would be better described as a homogeneous fluid-like substance instead of a cloud of massive particle. Experiments searching for elastic scattering are entirely insensitive in this case. This very light Dark Matter behaves more like a new force acting very weakly on electrons and nuclei or affecting their spin.

In this case the expected effects are tiny and can only be observed in extremely precise measurements of fundamental constants and interactions.

This project is a truly multidisciplinary effort to enable the search for dark matter with high-precision atomic physics experiments. Many of these experiments have made enormous progress during the last decades, increasing their sensitivity by many orders of magnitude. These high-precision experiments can potentially measure the very minute effects exerted by interactions of light and very light dark matter.

The theoretical mechanism underlying the production of this type of dark matter in the universe helps, because it predicts resonantly enhanced time-dependent signals, if the experiment can be designed to pick it up. Depending on the specific interaction, one dedicated or a variety of experiments might be the right strategy.

In order to answer this question a consistent theoretical framework will be developed taking into account the complex structure of quantum field theories necessary to describe dark matter at high energies. Even though high-precision experiments are performed at rather low energies compared to collider experiments or even some astrophysical processes these calculations are necessary to correctly derive observables and correlations between observables for these experiments.

This framework further makes the different experimental approaches comparable and existing limits can be used to optimise future experiments. With this in hand we can collaborate with atomic physicists throughout the UK to design an experimental programme exploiting the untapped potential of high-precision experiments to search for and potentially discover dark matter.