Signal proxy and radiative Bhabha background studies : contributions to the search for invisibly decaying dark photons at Belle II
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Crook, Daniel Weston Mckay
issued: 2023-08-31T18:03:51Z
issued: 2023
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The nature of dark matter is one of the greatest extant mysteries in physics. Many hypotheses have been proposed to explain dark matter, but none have ever been substantiated. Some of these hypotheses propose dark sectors, i.e., entire families of dark matter particles. One such hypothesis is that of the dark photon, a massive, gauge boson which would be the mediator of the dark electromagnetic force. The dark photon would couple feebly to the photon, and thereby be producible through e⁺e⁻ annihilation at a particle collider. Described here are contributions toward a search for the dark photon at Belle II, an electron-positron collider experiment in Japan. This search focuses on invisible decays of the dark photon, with a single initial-state radiation photon serving as the only evidence of the production and decay. Due to the delicate nature of this event signature, the dark photon search requires a carefully constructed set of event requirements and vetoes that remove as much background as possible without removing a large amount of the signal. To further this goal, two control samples were designed. One control sample is of a clean radiative dimuon sample, used as a signal proxy, while the other is of the radiative Bhabha background. These control samples are then used to design vetoes and selection criteria for the search for the dark photon at Belle II, termed the single-photon analysis.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/85729
note: Signal proxy and radiative Bhabha background studies:contributions to the search for invisibly decaying darkphotons at Belle IIbyDaniel Weston Mckay CrookB.Sc., McGill University, 2021A THESIS SUBMITTED IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FOR THE DEGREE OFMaster of ScienceinTHE FACULTY OF GRADUATE AND POSTDOCTORALSTUDIES(Physics)The University of British Columbia(Vancouver)August 2023© Daniel Weston Mckay Crook, 2023The following individuals certify that they have read, and recommend to the Fac-ulty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled:Signal proxy and radiative Bhabha background studies: contributionsto the search for invisibly decaying dark photons at Belle IIsubmitted by Daniel Weston Mckay Crook in partial fulfillment of the require-ments for the degree of Master of Science in Physics.Examining Committee:Christopher Hearty, Professor, Physics and Astronomy, UBCSupervisorJanis McKenna, Professor, Physics and Astronomy, UBCSupervisory Committee MemberiiAbstractThe nature of dark matter is one of the greatest extant mysteries in physics. Manyhypotheses have been proposed to explain dark matter, but none have ever beensubstantiated. Some of these hypotheses propose dark sectors, i.e., entire familiesof dark matter particles. One such hypothesis is that of the dark photon, a massive,gauge boson which would be the mediator of the dark electromagnetic force. Thedark photon would couple feebly to the photon, and thereby be producible throughe+e− annihilation at a particle collider. Described here are contributions toward asearch for the dark photon at Belle II, an electron-positron collider experiment inJapan. This search focuses on invisible decays of the dark photon, with a singleinitial-state radiation photon serving as the only evidence of the production anddecay. Due to the delicate nature of this event signature, the dark photon searchrequires a carefully constructed set of event requirements and vetoes that removeas much …
has type: Thesis/Dissertation
date issued: 2023-11
is shown at: 10.14288/1.0435692
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: Hearty, Christopher
type: Text
identifier URI: http://hdl.handle.net/2429/85729