This thesis presents a measurement of the mass, natural width, and signal strength, defined as the yield normalized to the Standard Model prediction, of the Higgs boson in the \(H \rightarrow ZZ^{(*)} \rightarrow 4l\) decay channel using an approach which utilizes event-by-event detector response information. The measurement is performed on p-p collision data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The data corresponds to an integrated luminosity of \(25 fb^{-1}\) with center-of-mass energies of 7 TeV and 8 TeV. The measured mass of the Higgs boson is \(m_H = 124.57_{-0.43}^{+0.48} GeV\). The signal strength was estimated at \(\mu = 1.76_{-0.37}^{+0.46}\). Finally, the natural width of the Higgs was determined to be < 2.6 GeV with 95% confidence. The event-by-event approach used in this analysis involves the parameterization of the behavior of single leptons in the ATLAS detector and the convolution of a mass response with the Higgs truth distribution to derive the reconstruction level signal model. / Physics

We obtain the characteristic relaxation rates and relaxation modes of a Bose gas in three regimes. The classical regime corresponds to a classical gas of hard spheres and the quantum regime corresponds to an interacting quantum Bose gas with no Bose-Einstein condensate present. In the condensed regime a Bose-Einstein condensate is present and modifies the behavior of the gas. In each regime there is a different kinetic equation that describes the evolution of the relevant distribution function. The classical kinetic equation is the Boltzmann equation and the quantum kinetic equation with no condensate present is the Uehling-Uhlenbeck equation. When a condensate is present, we derive a new kinetic equation that describes the evolution of the momentum distribution of Bogoliubov excitations or bogolons. For each of the three kinetic equations, we linearize the collision integral and use it to generate the elements of a collision matrix. The eigenvalues of this matrix give us the characteristic relaxation rates and the eigenvectors give us the relaxation modes. We report numerical results for the eigenvalues in each regime as the particle species, density and temperature of the gas are varied. / text

No description available.

Le mécanisme de Higgs, introduit en 1964, propose une solution à un problème majeur du modèle standard de la physique des particules : l'origine de la masse. Ce mécanisme prédit l'existence d'un boson scalaire, de masse non prédite par la théorie et qui n'a encore jamais été observé expérimentalement (Juin 2012). Le Tevatron, un accélérateur hadronique basé à Fermi National Accelerator Laboratory près de Chicago, a permis la prise de données à l'aide des deux détecteurs CDF et DØ depuis 1983 jusqu'en septembre 2011. Accumulant une statistique de près de 10fb-1 à analyser. La production associée du Higgs et d'un boson vecteur est le canal principal de recherche pour un Higgs standard léger. A l'aide des données collectées par DØ, nous recherchons ce mode de production. La production du boson de Higgs étant très rare, nous avons développé des techniques sophistiquées de manière à améliorer la sensibilité au signal, telles que l'identification des jets de quarks beaux ou encore des méthodes basées sur des discriminants multivariés. Au final, une approche statistique nous permet de poser une limite supérieure sur le taux de production du Higgs observé (resp. attendu) rapporté aux prédictions du modèle standard. Les résultats obtenus dans le canal WH avec la statistique finale de l'expérience DØ au Tevatron sont de 3.15 (resp. 3.97) pour un boson de Higgs de 115 GeV/C2.

Eine Messung der W-Boson Polarisation in Topquark-Zerfaellen wird vorgestellt. Es wurden Topquarks untersucht, welche in Proton-Proton Kollisionen bei einer Schwerpunktsenergie von sqrt{s} = 7 TeV am LHC erzeugt wurden. Der Datensatz basiert auf einer integrierten Luminositaet von 4.7 fb-1 und wurde mit dem ATLAS-Detektor gesammelt. Die Messung wurde im Lepton+Jets Kanal durchgefuehrt, welcher durch ein isoliertes Elektron oder Myon, fehlende transversale Energie und mindestens vier Jets charakterisiert wird. Einer der Jets muss als b-Jet identifiziert sein. Zum Studium der W-Boson Polarisation wurde die Winkelverteilung des geladenen Leptons im Ruhesystem des W-Bosons verwendet. Das Ereignis wurde vollstaendig mit Hilfe eines kinematischen Likelihood-Fits rekonstruiert. Die Anteile der linkshaendigen, rechtshaendigen und longitudinal polarisierten W-Bosonen wurden durch einen gebinnten Likelihood-Fit an die Datenverteilung bestimmt. Ein kombinierter Likelihood-Fit wird durchgefuehrt, um die W-Helizitaetsanteile fuer den Lepton+Jets Kanal zu bestimmen.

The discovery of a charged Higgs boson (H±) would be a clear indication for physics beyond the Standard Model. This thesis describes searches for charged Higgs bosons with the ATLAS experiment at CERN’s Large Hadron Collider (LHC). The first data collected during the LHC Run 1 is analysed, searching for a light charged Higgs boson (mH±&lt;mtop), which decays predominantly into a tau-lepton and a neutrino. Different final states with one or two leptons (electrons or muons), as well as leptonically or hadronically decaying taus, are studied, and exclusion limits are set. The background arising from misidentified non-prompt electrons and muons was estimated from data. This so-called "Matrix Method'' exploits the difference in the lepton identification between real, prompt, and misidentified or non-prompt electrons and muons. The Matrix Method is used in all charged Higgs boson searches in this thesis. In 2024 the LHC will be upgraded into a High Luminosity LHC (HL-LHC). The ATLAS detector is expected to collect around 300 fb-1 of collision data until 2022, whereas the HL-LHC will deliver about 250-300 fb-1 of data per year. This will increase the mean number of interactions per bunch crossing, resulting in larger particle fluxes. This puts challenging requirements on the electronics. In order to keep trigger and data rates at manageable levels, new trigger concepts require more intelligence at early stage which possibly results in more cables and connectors, inside the detector which lead to degraded performance of the detector system. This thesis presents new concepts using wireless technology at 60 GHz, in order add more data links inside the detector system without adding much material. Patch antennas have been developed, operating at 60 GHz. Manufacture methods have been investigated, and the fabrication tolerances and bandwidth of these antennas have been studied. Also, concepts of using passive repeaters have been investigated, to make the 60 GHz signal pass boundaries. These repeaters can be used to connect intelligence inside the detector, but also for reading out data from the whole detector radially.

Heidelberg, Univ., Diplomarbeit, 1999.

Thesis (M.SC.) - Carleton University, 2007. / Includes bibliographical references (p. 103-107). Also available in electronic format on the Internet.

Techn. Hochsch., Diss., 2002--Aachen.

Universiẗat, Diss., 2003--Wuppertal.