Dark Matter from the Top - Simplified Models of Flavoured Dark Matter in Dark Minimal Flavour Violation

Abstract

The mystery of dark matter is one of the biggest—if not the biggest—open questions in modern day physics. Dark matter (DM), connecting elements of particle physics and cosmology, poses a diverse, challenging and interesting field of research. In this thesis, we study the phenomenology of simplified models of flavoured dark matter (FDM) beyond Minimal Flavour Violation (MFV). For the first time, two models, coupling a dark matter flavour triplet to the Standard Model (SM) up-quark flavour triplet and to the SM left-handed quark-doublets respectively, are studied in the framework of Dark Minimal Flavour Violation (DMFV). The concept of DMFV has been introduced recently, allowing for a DM-quark coupling matrix of generic flavour structure. Hence, in this framework, the DM-quark coupling matrix constitutes a new source of both flavour and CP violation. We impose constraints from flavour experiments, the observed relic abundance, direct detection searches and new physics searches at colliders on the models, finding a rich phenomenology with an interesting interplay of effects. Among the multitude of effects, we especially want to emphasize the observed lower bound on the dark matter mass, resulting from the combined constraints. This lower bound significantly increases in light of future direct detection experiments, raising the chances to discover dark matter. This analysis hence constitutes a strong motivation for ongoing direct detection searches. Overall, we find that the combined analysis favours the scenario of top-flavoured dark matter, i.e. a DM relic which couples primarily to the SM top-quark. Furthermore, we identify areas of valid parameter space which are far different from the valid parameter space in the MFV limit. In conclusion, going beyond MFV is found to be well motivated, with DMFV as an excellent guidance.