Beyond MET: Long-Lived Particles at the LHC

Traditional searches for dark matter at the LHC rely on large missing transverse energy, or MET. I describe here, models that are inspired by co-annihilating, co-scattering or freeze-in dark matter that are not visible in MET searches, but require specialised searches to be seen. A feature of these models is the presence of a mediator particle that can be produced in large numbers at the LHC, but has a long lifetime. We therefore need a combination of different searches like displaced leptons, disappearing and heavy charged tracks to cover all interesting phase space.