Displaced vertex search for heavy neutral leptons using the ATLAS detector
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Trischuk, Dominique
issued: 2022-02-10T18:59:34Z
issued: 2022
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: This dissertation presents a search for long-lived heavy neutral leptons (HNLs) in proton-proton collisions at the Large Hadron Collider (LHC). The Standard Model (SM) of particle physics is an extremely successful theory and many of its major predictions have been precisely confirmed. However, the existence of neutrinos, with small nonzero masses, suggests that the SM is incomplete. Introducing HNLs into the SM is a natural way to generate the light neutrino masses through a seesaw mechanism. Theories that postulate the existence of such particles can also explain the asymmetry between matter and anti-matter in our universe and models with at least three HNLs provide a dark matter candidate. This experimental search uses ATLAS data collected between 2015 and 2018 at a centre-of-mass energy of 13 TeV. A non-standard technique is used to search for a displaced vertex from particle trajectories produced in the HNL decay to leptons. The dominant background from uncorrelated leptons crossing in the ATLAS detector is estimated using an object shuffling method. The reconstructed HNL mass is used to discriminate between signal and background. No excess of events is observed and constraints on the strength of the interactions between HNLs and neutrinos are imposed in various scenarios. This dissertation also presents new methods to study the readout system and performance of a silicon strip tracking detector. The LHC is currently undergoing upgrades that will enable it to produce more than ten times the data that has already been collected. To meet the requirements of this challenging new environment, an all-silicon particle tracking system will be installed in ATLAS.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/80822
note: Displaced Vertex Search For HeavyNeutral Leptons Using The ATLASDetectorbyDominique TrischukB.Sc., The University of Toronto, 2017A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinTHE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES(Physics)THE UNIVERSITY OF BRITISH COLUMBIA(Vancouver)February 2022© Dominique Trischuk 2022The following individuals certify that they have read, and recommend to the Faculty of Grad-uate and Postdoctoral Studies for acceptance, the dissertation entitled:Displaced Vertex Search For Heavy Neutral Leptons Using The ATLASDetectorsubmitted by Dominique Trischuk in partial fulfillment of the requirements forthe degree of Doctor of Philosophyin PhysicsExamining Committee:Colin Gay, Physics & Astronomy, UBCSupervisorAlison Lister, Physics & Astronomy, UBCCo-SupervisorDouglas Bryman, Physics & Astronomy, UBCUniversity ExaminerRoman Krems, Chemistry, UBCUniversity ExaminerAdditional Committee Members:Gary Hinshaw, Physics & Astronomy, UBCSupervisory Committee MemberAriel Zhitnitsky, Physics & Astronomy, UBCSupervisory Committee MemberiiAbstractThis dissertation presents a search for long-lived heavy neutral leptons (HNLs) in proton-proton collisions at the Large Hadron Collider (LHC). The Standard Model (SM) of particlephysics is an extremely successful theory and many of its major predictions have been preciselyconfirmed. However, the existence of neutrinos, with small nonzero masses, suggests that theSM is incomplete. Introducing HNLs into the SM is a natural way to generate the light neutrinomasses through a seesaw mechanism. Theories that postulate the existence of such particlescan also explain the asymmetry between matter and anti-matter in our universe and modelswith at least three HNLs provide a dark matter candidate. This experimental search usesATLAS data collected between 2015 and 2018 at a centre-of-mass energy of 13 TeV. A non-standard technique is used to search for a displaced ver…
has type: Thesis/Dissertation
date issued: 2022-05
is shown at: 10.14288/1.0406559
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Gay, Colin
contributor: Lister, Alison
type: Text
identifier URI: http://hdl.handle.net/2429/80822