A search for the Standard Model Higgs boson in the process ZH → ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ in 4.1 fb<sup>-1</sup> of CDF II data

PDF Version Also Available for Download.

Description

The standard model of particle physics provides a detailed description of a universe in which all matter is composed of a small number of fundamental particles, which interact through the exchange of force - carrying gauge bosons (the photon, W <sup>±</sup>, Z and gluons). The organization of the matter and energy in this universe is determined by the effects of three forces; the strong, weak, and electromagnetic. The weak and electromagnetic forces are the low energy manifestations of a single electro-weak force, while the strong force binds quarks into protons and neutrons. The standard model does not include gravity, as ... continued below

Physical Description

204 p.

Creation Information

Shalhout, Shalhout Zaki May 1, 2010.

Context

This thesis or dissertation is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this document can be viewed below.

Who

People and organizations associated with either the creation of this thesis or dissertation or its content.

Author

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this thesis or dissertation. Follow the links below to find similar items on the Digital Library.

Description

The standard model of particle physics provides a detailed description of a universe in which all matter is composed of a small number of fundamental particles, which interact through the exchange of force - carrying gauge bosons (the photon, W <sup>±</sup>, Z and gluons). The organization of the matter and energy in this universe is determined by the effects of three forces; the strong, weak, and electromagnetic. The weak and electromagnetic forces are the low energy manifestations of a single electro-weak force, while the strong force binds quarks into protons and neutrons. The standard model does not include gravity, as the effect of this force on fundamental particles is negligible. Four decades of experimental tests, spanning energies from a few electron-volts (eV) up to nearly two TeV, confirm that the universe described by the standard model is a reasonable approximation of our world. For example, experiments have confirmed the existence of the top quark, the W<sup>±</sup> and the Z bosons, as predicted by the standard model. The latest experimental averages for the masses of the top quark, W<sup>±</sup> and Z are respectively 173.1 ± 0.6(stat.) ± 1.1(syst.), 80.399 ± 0.023 and 91.1876 ± 0.0021 GeV/c<sup>2</sup>. The SM is a gauge field theory of zero mass particles. However, the SM is able to accommodate particles with non-zero mass through the introduction of a theoretical Higgs field which permeates all of space. Fermions gain mass through interactions with this field, while the longitudinal components of the massive W<sup>±</sup> and Z are the physical manifestations of the field itself. Introduction of the Higgs field, directly leads to the predicted existence of an additional particle, the Higgs boson. The Higgs boson is the only particle of the standard model that has not been observed, and is the only unconfirmed prediction of the theory. The standard model describes the properties of the Higgs boson in terms of its mass, which is a free parameter in the theory. Experimental evidence suggests that the Higgs mass has a value between 114.4 and 186 GeV/c<sup>2</sup>. Particles with a mass in this range can be produced in collisions of less massive particles accelerated to near the speed of light. Currently, one of only a few machines capable of achieving collision energies large enough to potentially produce a standard model Higgs boson is the Tevatron proton-antiproton collider located at Fermi National Accelerator Laboratory in Batavia, Illinois. This dissertation describes the effort to observe the standard model Higgs in Tevatron collisions recorded by the Collider Detector at Fermilab (CDF) II experiment in the ZH →ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ production and decay channel. In this process, the Higgs is produced along with a Z boson which decays to a pair of electrons or muons (Z →ℓ<sup>+</sup>ℓ<sup>-</sup>), while the Higgs decays to a bottom anti-bottom quark pair (H → b$\bar{b}$). A brief overview of the standard model and Higgs theory is presented in Chapter 2. Chapter 3 explores previous searches for the standard model Higgs at the Tevatron and elsewhere. The search presented in this dissertation expands upon the techniques and methods developed in previous searches. The fourth chapter contains a description of the Tevatron collider and the CDF II detector. The scope of the discussion in Chapter 4 is limited to the experimental components relevant to the current ZH →ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ search. Chapter 5 presents the details of object reconstruction; the methods used to convert detector signals into potential electrons, muons or quarks. Chapter six describes the data sample studied for the presence of a ZH →ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ signal and details the techniques used to model the data. The model accounts for both signal and non-signal processes (backgrounds) which are expected to contribute to the observed event sample. Chapters 7 and 8 summarize the event selection applied to isolate ZH →ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$} candidate events from the data sample, and the advanced techniques employed to maximize the separation of the signal from background processes. Chapters 9 and 10 present the systematic uncertainties affecting our modeling of the data sample and the results of the search. Chapter 11 presents a discussion of ZH →ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ in the context of the overall Tevatron efforts to observe a standard model Higgs signal.

Physical Description

204 p.

Language

Identifier

Unique identifying numbers for this document in the Digital Library or other systems.

  • Report No.: FERMILAB-THESIS--2010-33
  • Grant Number: AC02-07CH11359
  • DOI: 10.2172/985419 | External Link
  • Office of Scientific & Technical Information Report Number: 985419
  • Archival Resource Key: ark:/67531/metadc1014200

Collections

This document is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this thesis or dissertation?

When

Dates and time periods associated with this thesis or dissertation.

Creation Date

  • May 1, 2010

Added to The UNT Digital Library

  • Oct. 14, 2017, 8:36 a.m.

Description Last Updated

  • Oct. 25, 2017, 4:31 p.m.

Usage Statistics

When was this document last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 1

Interact With This Thesis Or Dissertation

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

International Image Interoperability Framework

IIF Logo

We support the IIIF Presentation API

Shalhout, Shalhout Zaki. A search for the Standard Model Higgs boson in the process ZH → ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ in 4.1 fb<sup>-1</sup> of CDF II data, thesis or dissertation, May 1, 2010; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc1014200/: accessed December 14, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.