Search for new physics with soft displaced vertex and missing transverse momentum at CMS

A search for long-lived particles (LLPs) using final states including a soft displaced vertex, significant missing transverse momentum, and a jet from initial state radiation is reported. Compressed bino-stop and bino-wino coannihilation models are used as benchmark signal models. In those models, LLPs decay to a lightest supersymmetry particle (LSP) and standard model particles. This search aims to be sensitive to soft LLPs that not only can travel 20 cm before decay, but also carries very little energy that is less than 25 GeV. Displaced vertices are reconstructed using a customized algorithm based on the adaptive vertex finder. A data-driven background estimation is used to predict the number of background events in the signal regions. The search excludes top squark with masses less than 550–1100 GeV and wino-like neutralinos with masses less than 220–540 GeV, depending on the signal parameters. It sets the most stringent limits to date for the long-lived top squark and bino-wino coannihilation models.