Juliette Alimena, 15.04.2020


Searches for Long-Lived Particles at the LHC


Particles with large lifetimes are an important possibility in the search for new phenomena, especially in the search for the particle nature of dark matter. Conventional searches at the CERN LHC target promptly decaying particles, but standard model (SM) particle lifetimes span a very wide range, and long lifetimes can generically appear in scenarios beyond the standard model (BSM). In fact, long-lived particles (LLPs) are predicted by many not yet excluded BSM scenarios such as gauge-mediated supersymmetry breaking models, heavy neutral leptons, and dark photons, to name a few. Thus, LLPs have a great potential for discovery. When produced at the LHC, these LLPs have a distinct experimental signature: they can decay far from the primary proton-proton interaction, or even completely pass through a detector, such as ATLAS or CMS, before decaying. After introducing LLP searches at the LHC, I will present a search for the decays of heavy LLPs that come to rest in the CMS detector. Their decays would be visible during periods of time well separated from proton-proton collisions. Two decay scenarios of stopped LLPs will be shown: a hadronic decay detected in the calorimeter and a decay into muons detected in the muon system. I will also present a proposal for a Helmholtz Young Investigator Group, to be based at DESY and in collaboration with RWTH Aachen University.

Host: Lutz Feld