Search for charged long-lived particles at the Future Circular Collider (FCC-ee)
Long-lived particles (LLPs) have emerged as a compelling signature of physics beyond the standard model, offering unique discovery opportunities at current and future colliders. We present an analysis of charged LLPs leading to signatures with kinked tracks and displaced vertices. Using timing information the search is extended to detector-stable LLPs. We explore the discovery prospects of such particles at the Future Circular Collider~(FCC-ee), a proposed $e^{+}e^{-}$ collider. The clean collision environment of FCC-ee and excellent tracking performance of the IDEA detector enhance the sensitivity to kinked-track signatures, which are considerably more challenging to reconstruct in the high-occupancy environment of hadron colliders. The excellent timing resolution of the timing layer enables us to infer the mass of the detector stable particles. As a benchmark the stau pair production in the gauge mediated supersymmetry breaking (GMSB) within the minimal supersymmetric standard model scenario is considered. In this model the lightest supersymmetric particle is a gravitino and the next-to-lightest supersymmetric particle is the stau, the superpartner of the tau lepton. Discovery sensitivity up to the kinematic limit is obtained for the $ZH$ and $t\bar{t}$ runs of the planned FCC-ee operation. We demonstrate that a potential discovery would allow for a precise $\tildeτ$ mass measurement.