COLLOQUIUM: `FIMP, the new WIMP' by Susanne Westhoff (RU Nijmegen)


After decades of research, the nature of dark matter remains a mystery. Searches for dark matter candidates have been driven by theory assumptions like supersymmetry, which seemed to point towards Weakly Interacting Massive Particles (WIMPs) around the scale of electroweak symmetry breaking.

In this talk, I advocate for an observation-driven approach to dark matter. When combining information from astrophysics and laboratory searches, a new cool kid in town emerges: Feebly Interacting Massive Particles (FIMPs) around the MeV-GeV scale, which seem cosmologically viable and predict interesting new signatures in the lab.

Searches for long-lived particles play a prominent role in establishing evidence for FIMP dark matter, because they probe the tiniest interactions. I will present recent results from the lifetime frontier and point out new ideas to pin down the FIMP.