Reinterpretation of CMS search for LLPs using endcap muon detectors

We present a recast and sensitivity projection in different benchmark models of a recent result from CMS (https://arxiv.org/abs/2107.04838) that uses the endcap muon detectors as sampling calorimeter to identify displaced showers produced by decays of long-lived particles (LLPs). The exceptional shielding provided by the steel return-yoke interleaved between the CMS muon detector stations drastically reduces the SM background that limits other existing searches. We present a new dedicated Delphes module for fast detector response simulation of the muon detector showers and the recast of the novel CMS search to low mas LLP models using the new Delphes module. We also discuss the complementarity of the CMS search to dedicated LLP proposed and existing experiments.