Search for Inelastic Dark Matter with Soft Displaced Electrons Using CMS Run2 Data at sqrt(s) = 13 TeV

This talk presents a new search for inelastic dark matter (iDM) in the dielectron final state using data collected with the CMS detector during Run2 at sqrt(s) = 13 TeV. The iDM model proposes that dark matter exists in multiple states with small mass splitting, interacting with Standard Model particles via inelastic scattering from the lighter to the heavier state, while elastic scattering is highly suppressed. As a compelling dark matter candidate, the iDM model can reconcile the null results from direct detection experiments and produce striking signatures at collider. One of the states can acquire a macroscopic lifetime, resulting in a distinct signature with soft, displaced leptons carrying transverse momentum on the order of 1 GeV and large missing transverse momentum. To enhance sensitivity to this challenging final state, we employ a dedicated electron reconstruction algorithm that improves efficiency at low transverse momentum and high displacement by relying on tracker-based seeding. The search probes dark matter scenarios with mean proper lifetimes between 1 and 100 mm, complementing and extending limits from other iDM searches in both direct and indirect detection experiments.