Wider research context/theoretical framework The origin of dark energy is one of the greatest puzzles in modern physics. Cosmological observations indicate that our Universe is currently expanding at an accelerated rate. An unknown substance, called dark energy, that fills the Universe is the most prominent explanation for this acceleration. Naturally, the existence of new hypothetical scalar fields has been postulated, which couple to gravity and can account for dark energy. Those new scalars generically lead to new interactions, so-called fifth forces. However, measurements with high precision at solar as well as terrestrial scales were so far unable to detect any fifth forces.
Hypotheses/research questions/objectives Many high precision tabletop experiments are in principle able to detect such hypothetical new scalar fields. Among those are three performed by members of the Neutron and Quantum Physics group of the Atominstitut/TU Wien. This project addresses the theoretical analysis relevant for the detection of several prominent hypothetical scalar fields, and as such the possible detection of dark energy, with these experiments. The analysis will also include data from Lunar Laser Ranging to provide complementary access to the astrophysical regime.
Approach/methods For the practical realization of the aims of this project we will make use of methods that have been employed by our working group previously in related contexts. For the analysis of the scalar fields we adapt and further develop methods, which in turn are based on the well established methods of (quantum) field theory including a mixture of analytical as well as numerical methods. Level of originality/innovation To discover the nature of dark energy constitutes certainly one of the most important tasks that confronts physicists and, in particular, cosmologists in our time. Right now tabletop experiments have obtained the sensitivities necessary to either detect or almost rule out specific dark energy models. In this project the theoretical analysis for three tabletop experiments employed in the search for dark energy will be carried out with all groups being members of the same institute. The results obtained by this collaboration potentially probe new regions of parameter space of individual dark energy models, which is crucial to either detect or rule out any of those models. A further focus of this project concerns the investigation of the interaction of dark energy models with the experimental probes fully at the quantum level.
Primary researchers involved The project leader, Mario Pitschmann, has experience in all areas relevant for successfully carrying out the aims of this research project. He will be funded from the TU Wien. The PostDoc Christian Käding is an expert on non-equilibrium quantum field theory and scalar fields that arise in the contexts of dark energy and modified gravity theories. Further support for this project should be provided by a PhD.
