There are many indications that the standard model of particle physics does not provide a full description of the fundamental forces of nature -- one of them being the existence of the cosmological dark matter, which cannot be composed of any presently known form of matter. The last decades have seen various attempts to search for new physics with classical methods from nuclear or particle physics, however without finding any undisputed signal.
Almost all these attempts implicitly assume that the new particles being searched for have sizeable interactions with standard model particles. From a theoretical point of view, however, there is no compelling reason for why this has to be the case. In particular, there could be a hidden, or 'dark', sector of new particles and interactions that is completely decoupled from the visible sector and hence not accessible to any direct searches. Remarkably, there is still a considerable cosmological lever arm on such scenarios, reaching from probes that test the evolution of the universe during the Big Bang to probes relevant at much later times, when the first galaxies form. The project will explore these probes, try to refine them, and work out consequences
for concrete particle physics realizations that fall into this broad class of models.
The project requires an excellent understanding of cosmology and very good skills in quantum field theory. The focus is on analytical analysis, aided by algebraic programs like mathematica. For more advanced applications, good programming skills may
be an advantage.