Suche nach dem Higgs-Boson in hadronischen Endzuständen mit fehlender Energie am L3-Experiment bei LEP
type: CreativeWork
description: This thesis presents searches for the Higgs boson, which is predicted by the Standard Model of Particle Physics and its extensions in order to endow fermions and bosons with their observed masses. While the Standard Model predicts only one Higgs boson "H", the Minimal Supersymmetric Extension contains five Higgs bosons. This analysis refers to the light neutral "h", which has nearly the same properties as the Standard Model Higgs boson. The analyses are based on data taken by the L3 experiment at the Large Electron Positron Collider (LEP) near Geneva during the years 1998 until 2000, which corresponds to an integrated luminosity of 629.7/pb and which were collected in a center-of-mass energy range from 189 GeV to 209 GeV. The Higgs boson searches presented here analyse the data with regard to hadronic events with missing energy, since the visible energy is reduced compared to the total energy given by the LEP collider. According to theoretical prediction these final states can be produced via the Higgs-strahlung process, e+e- --> Z* --> HZ oder e+e- --> Z* --> hZ, where a Higgs boson is radiated by a virtual Z boson that subsequently goes on-shell. The first part of the analysis is devoted to the search for the Standard Model Higgs boson in the reaction e+e- --> HZ --> q(anti-)q nu(anti-)nu, which is the second most frequent channel for Higgs production. The observed jets stem from the Higgs boson decaying into a quark- antiquark pair, being a b(anti-)b pair with about 75% probability in the mass range under consideration. With a probability of 20% the Z boson goes in neutrinos, so that the visible energy of the events in comparison to the center-of-mass energy shows a deficit according to the mass of the Z. The initial selection requires high multiplicity in order to separate hadronic and leptonic events and a minimum value of missing energy. Subsequently a neural network is used to search for Higgs decaying into b quarks, which in turn result in jets with B mesons…
abstract: This thesis presents searches for the Higgs boson, which is predicted by the Standard Model of Particle Physics and its extensions in order to endow fermions and bosons with their observed masses. While the Standard Model predicts only one Higgs boson "H", the Minimal Supersymmetric Extension contains five Higgs bosons. This analysis refers to the light neutral "h", which has nearly the same properties as the Standard Model Higgs boson. The analyses are based on data taken by the L3 experiment at the Large Electron Positron Collider (LEP) near Geneva during the years 1998 until 2000, which corresponds to an integrated luminosity of 629.7/pb and which were collected in a center-of-mass energy range from 189 GeV to 209 GeV. The Higgs boson searches presented here analyse the data with regard to hadronic events with missing energy, since the visible energy is reduced compared to the total energy given by the LEP collider. According to theoretical prediction these final states can be produced via the Higgs-strahlung process, e+e- --> Z* --> HZ oder e+e- --> Z* --> hZ, where a Higgs boson is radiated by a virtual Z boson that subsequently goes on-shell. The first part of the analysis is devoted to the search for the Standard Model Higgs boson in the reaction e+e- --> HZ --> q(anti-)q nu(anti-)nu, which is the second most frequent channel for Higgs production. The observed jets stem from the Higgs boson decaying into a quark- antiquark pair, being a b(anti-)b pair with about 75% probability in the mass range under consideration. With a probability of 20% the Z boson goes in neutrinos, so that the visible energy of the events in comparison to the center-of-mass energy shows a deficit according to the mass of the Z. The initial selection requires high multiplicity in order to separate hadronic and leptonic events and a minimum value of missing energy. Subsequently a neural network is used to search for Higgs decaying into b quarks, which in turn result in jets with B mesons…
author: Zöller, Marc Henning
language: ger
keywords: info:eu-repo/classification/ddc/530, Elektron-Positron-Vernichtung, Higgs-Teilchen, L3-Detektor, Physik, Higgs, LEP, L3, CERN
date published: 2005
date modified: 2026-07-30T19:43:19Z
provider: RWTH Aachen University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Publikationsserver der RWTH Aachen University