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Open Access Publications from the University of California

A Search for Dark Particles Produced in Association with the Z Boson and Jets in 13 TeV Proton-Proton Collisions

  • Author(s): Hashemi, Bobak Taleb
  • Advisor(s): Wüerthwein, Frank
  • Yagil, Avraham
  • et al.
Abstract

This thesis presents the results of a search for new physics in proton-proton collisions at the Large Hadron Collider, running with 13 TeV center of mass energy, using data gathered by the Compact Muon Solenoid (CMS). The search targets TeV mass-scale dark matter candidates and uses final states with two opposite-charge and same-flavor light leptons (electrons or muons) having dilepton mass consistent with the Z boson, at least 2 hadronic jets, and at least 100 GeV of transverse momentum imbalance. The thesis contains a historical introduction to particle physics, brief reviews of the standard model and supersymmetry, an in-depth discussion of the acquisition

of data by the Large Hadron Collider and CMS detector, and a pedagogical overview of the analysis methods used. No statistically significant deviation is found from the expected standard model background. The search results are presented and interpreted in the context of several simplified models of supersymmetry, including a model of Gauge Mediated Supersymmetry- Breaking (GSMB) with gluino production and models with Electroweakino production. The excluded mass ranges for these models are advanced by approximately 50-100% with respect to the best previous searches. This work represents the current state of the art for their exclusion

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