  We propose a systematic programme to search for long-lived neutral particle
signatures through a minimal set of displaced searches requiring significant
missing transverse energy (dMETs).
  Our approach is to extend the well-established dark matter simplified models
to include displaced vertices. The dark matter simplified models are used to
describe the primary production vertex. A displaced secondary vertex,
characterised by the mass of the long-lived particle and its lifetime, is added
for the displaced signature. We show how these models can be motivated by, and
mapped onto, complete models such as gauge-mediated SUSY breaking and models of
neutral naturalness. We also outline how this approach may be used to extend
other simplified models to incorporate displaced signatures and to characterise
searches for long-lived charged particles. Displaced vertices are a striking
signature with virtually no backgrounds from SM processes, and thus provide an
excellent target for the high-luminosity run of the Large Hadron Collider. The
proposed models and searches provide a first step towards a systematic
broadening of the displaced dark matter search programme.
