Speaker
Description
We investigate the flavour structure of thermal dark matter in t-channel simplified models and identify which scenarios remain compatible with current flavour, direct-detection, and collider constraints. Using flavour symmetries and spurion expansions as organizing principles, we systematically chart the space of viable dark matter interactions within the frameworks of Minimal Flavour Violation, (U(2)^5), and Minimal Flavour Protection. We show how progressively weaker flavour symmetries enlarge the space of phenomenologically viable dark-sector couplings while maintaining controlled suppression of flavour-changing neutral currents and CP violation.
Focusing on representative leptophilic and quarkphilic benchmarks with singlet fermionic dark matter and scalar mediators, we perform a comprehensive phenomenological analysis combining relic-density constraints, flavour observables, direct detection, and collider searches. We study both Majorana and Dirac dark matter scenarios, consistently including coannihilation effects as well as Sommerfeld enhancement and bound-state contributions relevant for thermal freeze-out.
Our analysis quantifies the degree of flavour alignment required by present data and identifies the regions of parameter space where approximate flavour symmetries naturally emerge. In leptophilic scenarios, charged-lepton flavour violation provides some of the strongest probes of generic flavour structures, while future direct-detection experiments significantly extend the sensitivity for Dirac dark matter. In quarkphilic models, flavour-changing neutral currents and direct detection impose strong constraints on first-generation couplings, favouring interactions aligned with heavier flavours. Overall, our results demonstrate how flavour symmetries provide a powerful and systematic framework to classify and constrain thermal dark matter models beyond the minimal WIMP paradigm.