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Precision measurement of and search for dark matter in the transverse momentum spectra of Z bosons

By Dylan George. Hsu

Abstract

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2019Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 241-256).A measurement of the differential Z boson production cross section in proton-proton collisions is presented. It furnishes a precision test of the Standard Model, and constrains the parton distribution functions of the proton. Moreover, it is a building block for future measurements of the mass of the W± boson. A study of the efficiency of lepton identification algorithms is performed which drives the precision of the measurement at lower values of transverse momentum. In tandem, a search for new physics in events with a Z boson produced in association with large missing transverse momentum is presented. The results of this search are interpreted in the context of several dark matter models: generic spin-0 or spin-1 mediators, invisible decays of a Higgs-like boson, unparticles, and large extra spatial dimensions. A multivariate analysis was developed to enhance the sensitivity of the invisible Higgs interpretation. The theoretical uncertainty on the irreducible background from electroweak diboson processes is constrained by emulating the missing energy using pure control samples in the fully leptonic final states. The data were collected with the Compact Muon Solenoid detector at the Large Hadron Collider and correspond to an integrated luminosity of 35.9 fb-1. No significant deviations from the Standard Model are found.by Dylan George Hsu.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Physic

Topics: Physics.
Publisher: Massachusetts Institute of Technology
Year: 2019
OAI identifier: oai:dspace.mit.edu:1721.1/124575
Provided by: DSpace@MIT
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