Measurement of the Angular Distribution of the Electron From W {r_arrow} E = {Nu} decay, in P{Anti P} at {Radical}S = 1.8 Tev, as Function of P{Sub T}{Sup W}; Medida De La Distribucion Angular Del Electron De W en E + Neutrino en P{Anti P} a 1.8 Tev (open access)

Measurement of the Angular Distribution of the Electron From W {r_arrow} E = {Nu} decay, in P{Anti P} at {Radical}S = 1.8 Tev, as Function of P{Sub T}{Sup W}; Medida De La Distribucion Angular Del Electron De W en E + Neutrino en P{Anti P} a 1.8 Tev

The goal of this work was to study the behavior of the angular distribution of the electron form the decay of the W boson in a specific rest-frame of the W, the Collins-Soper frame. This thesis consists of four major divisions, each dealing with closely related themes: (a) Physics Background, (b) Description of the Hardware and General Software Tools, (c) Description of the Analysis and Specific Tools, and (d) Results and Conclusions. Each division is comprised of one or more chapters and each chapter is divided into sections and subsections.
Date: October 7, 1996
Creator: Ramos, M. I. M.
System: The UNT Digital Library
Photoproduction de Mesons sur le Nucleon aux Energies Intermediaire (in French) (open access)

Photoproduction de Mesons sur le Nucleon aux Energies Intermediaire (in French)

None
Date: December 1, 1996
Creator: Guidal, Michel
System: The UNT Digital Library
Search for the Higgs Boson and Technicolor Particles in p anti-p Colisions at sqrt(s) = 1.8 TeV (open access)

Search for the Higgs Boson and Technicolor Particles in p anti-p Colisions at sqrt(s) = 1.8 TeV

In the Standard Model (SM) of the elementary particles, the interactions among the known fundamental fermions (leptons and quarks) are mediated through gauge bosons which obey the symmetry: SU(3) {circle_times} SU(2) {circle_times} U(1). More precisely, the electroweak interaction [4-6] is described by a gauge symmetry SU(2) {circle_times} U(1) which is broken spontaneously. The electroweak symmetry breaking is implemented by the introduction of a complex scalar Higgs field which has a non-zero vacuum expectation value (vev). This way, the lagrangian of the theory remains invariant under SU(2) transformations, but quantization of the fields must start from a ground state which does not exhibit this symmetry, and therefore the full symmetry of the lagrangian is not manifest. Invariance of the theory under local SU(2) transformations implies the presence of vectorial gauge fields which mediate the electroweak interactions. The so called spontaneous symmetry breaking allows the quanta of these gauge fields, the W and Z bosons, to acquire a finite mass. The photon, the particle which mediates the electromagnetic interaction, remains massless. The Higgs boson is one of only two particles in the SM which have not yet been directly observed (the other is the {nu}{sub {tau}}, although there is indirect evidence of …
Date: November 1, 1999
Creator: Cortabitarte, Rocio Vilar & /Cantabria U., Santander
System: The UNT Digital Library
Search for Supersymmetric Particles in the dimuon channels (open access)

Search for Supersymmetric Particles in the dimuon channels

None
Date: July 1, 2004
Creator: Vu Anh, Tuan & /Orsay
System: The UNT Digital Library
Search for the electroweak production of the top quark in the D0 experiment (open access)

Search for the electroweak production of the top quark in the D0 experiment

None
Date: May 1, 2005
Creator: Agelou, Mathieu
System: The UNT Digital Library
Study of the Asymmetric Photoproduction of Charmed Mesons using Data from the FOCUS Experiment (open access)

Study of the Asymmetric Photoproduction of Charmed Mesons using Data from the FOCUS Experiment

Using data from the fixed target charm-photoproduction experiment, Fermilab FOCUS/E831, they studied the asymmetric production of the mesons: D{sup 0}, D{sup +} y D{sub s}{sup +}. Even when the asymmetry in the production of charm particles, defined as the ratio between particles and antiparticles, at next leading order in quantum chromodynamics (QCD) is almost zero, in data we observe asymmetries probably associate dto the fragmentation processes. Since these are the less understood phenomena in QCD, the results in the present work could be of great importance to understand them. We found asymmetries in the production of the mesons D{sup +} and D{sup 0} (statistic significant), for the D{sub s}{sup +} we only observed an asymmetry not conclusive. We also report a study of the production asymmetries vs. the kinematic variables: p{sub T}{sup 2} (square transversal momentum of the particles), p{sub L} or p{sub Z} (longitudinal momentum), x{sub F} (Feynman x) and E{sub {gamma}} (photon beam energy).
Date: May 1, 2005
Creator: Vazquez-Valencia, Elsa Fabiola
System: The UNT Digital Library
Search for supersymetric particles desintegrant itself in R-parite violee (coupling lambda_121) in a final state has three leptons (open access)

Search for supersymetric particles desintegrant itself in R-parite violee (coupling lambda_121) in a final state has three leptons

This thesis is dedicated to the study of the first data taken by the D0 detector during the Run II of the Tevatron. Supersymmetric particles have been search for in proton-antiproton collisions, with a center of mass energy of 1.96 TeV. In the framework of supersymmetry with R-parity violation, I have studied the pair production of Gauginos, leading to a pair of LSP ({chi}{sub 1}{sup 0}), each one decaying into ee{nu}{sub {mu}} or e{mu}{nu}{sub e} with a {lambda}{sub 121} coupling. The final state contains at least two electrons: I have thus paid special attention in this work to the methods concerning identification and mis-identification of electromagnetic particles, as well as reconstruction, triggering, and correction (of the reconstructed energy). In a selection of trileptons, with at least two electrons, and some transverse missing energy, we observed 0 event in the 350 pb{sup -1} of analyzed data, for 0,4{sub -0,05}{sup +0,35}(stat) {+-} 0,16 (sys) expected from the Standard Model contributions. In the signal considered in this analysis, the selection efficiency is around 12%. Results have been studied in two models: mSUGRA and MSSM. In mSUGRA model, limits on m{sub 1/2} and lightest gauginos's masses have been obtained, with tan{beta} = 5, A{sub …
Date: July 1, 2005
Creator: Magnan, Anne-Marie & /LPSC, Grenoble
System: The UNT Digital Library
Search for supersymmetric Higgs bosons at the Tevatron with the D0 experiment (open access)

Search for supersymmetric Higgs bosons at the Tevatron with the D0 experiment

None
Date: September 1, 2006
Creator: Michaut, Marine & /Orsay
System: The UNT Digital Library
Study of the S-wave K(pi) --> Amplitude Using the Decay D+ --> K-pi+pi+ (open access)

Study of the S-wave K(pi) --> Amplitude Using the Decay D+ --> K-pi+pi+

In this work the S-wave component of the K{pi} amplitude from decay of D{sup +} {yields} K{sup -}{pi}{sup +}{pi}{sup +} it is directly measured. The data come from the Fermilab E831/FOCUS experiment. The amplitude measurement is made using the partial wave analysis without any preliminary assumption about the nature of the S-wave component of the K{pi} system. The phase and magnitude of the S-wave amplitude are generic functions to be determined directly through the Dalitz plot fit. For the sake of comparison, our results the same decay is analyzed using the isobar model, which is the standard way to analyze the Dalitz plot. The data fit obtained with the partial wave analysis is better than the data fit from the isobar model. The phase variation with respect to the invariant mass K{pi} is compared with the measurement of the phase {delta}{sub I=1/2}{sup 0} (m{sub K{pi}}) from K{pi} {yields} K{pi} scattering. The difference between both analysis is discussed considering: a difference in the composition of the isospin components I = 1/2 and I = 3/2 of the K{pi} system between D{sup +} decay and the K{pi} {yields} K{pi} scattering; and the final state interaction involving all particles from decay.
Date: February 1, 2007
Creator: Machado, Ana Amelia Bergamini
System: The UNT Digital Library
Search for supersymmetric partner of bottom quark at d0 at Tevatron. Studies on missing transverse energy (open access)

Search for supersymmetric partner of bottom quark at d0 at Tevatron. Studies on missing transverse energy

Supersymmetry, extension of the Standard Model of Particle Physics (SM), is searched for by trying to observe the supersymmetric partner of bottom quark ({tilde b}). This search is performed using events with a final state comprising two acoplanar b-quark jets and missing transverse energy (MET) and coming from a sample of 992 pb{sup -1} of data collected by the D0 detector at the Tevatron, the Fermilab p{bar p} collider. The absence of an excess of events in comparison to MS expectations leads to exclude sb masses up to 201 GeV, neutralino masses up to 94 GeV. The MET has been studied under two points of view, because of its fundamental role in this search. First, at the level of the trigger system which allows the online selection candidate events, and then, within the framework of the ALPGEN generator, the simulation of the Z boson transverse momentum which appears as MET when the Z boson decays into neutrino.
Date: September 1, 2007
Creator: Calvet, Samuel Pierre
System: The UNT Digital Library
Recherche du boson de Higgs standard dans le canal WH a l'experience D0 aupres du Tevatron (open access)

Recherche du boson de Higgs standard dans le canal WH a l'experience D0 aupres du Tevatron

None
Date: September 1, 2008
Creator: Lellouch, Jeremie
System: The UNT Digital Library
Search for 1st Generation Leptoquarks in the eejj channel with the DZero experiment (open access)

Search for 1st Generation Leptoquarks in the eejj channel with the DZero experiment

An evidence of the existence of leptoquarks (LQ) would prove the validity of various extensions of the Standard Model of Particle Physics (SM). The search for first generation leptoquarks presented in this dissertation has been performed by analyzing a 1.02 fb{sup -1} sample of data collected by the D0 detector, events with a final state comprising two light jets and two electrons. The absence of an excess of events in comparison to SM expectations leads to exclude scalar LQ masses up to 292 GeV and vector LQ masses from 350 to 458 GeV, depending on the LQ-l-q coupling type. The great importance of a good jet energy measurement motivated the study of the instrumental backgrounds correlated to the calorimeter, as much as studies of the hadronic showers energy resolution in {gamma} + jets events.
Date: September 1, 2008
Creator: Barfuss, Anne-Fleur
System: The UNT Digital Library
Trigger Detectors of the Forward Muon System for the D0 Experiment (open access)

Trigger Detectors of the Forward Muon System for the D0 Experiment

None
Date: December 1, 2008
Creator: Vasilyev, I.
System: The UNT Digital Library
Measurement of the Cross Section of Charmed Hadrons and the Nuclear Dependence Alpha (open access)

Measurement of the Cross Section of Charmed Hadrons and the Nuclear Dependence Alpha

With data from the SELEX experiment we study charm hadro-production. We report the differential production cross sections as function of the longitudinal and transverse momentum, as well as for two different target materials, of 14 charmed hadron and/or their decay modes. This is the most extensive study to date. SELEX is a fixed target experiment at Fermilab with high forward acceptance; it took data during 1996-1997 with 600 GeV/c {Sigma}{sup -} and {pi}{sup -}, and 540 GeV/c proton and {pi}{sup +} beams. It used 5 target foils (two copper and three diamond). We use the results to determine {alpha}, used in parametrizing the production cross section as {infinity} A{sup {alpha}}, where A is the mass number of the target nuclei. We found within our statistics that {alpha} is independent of the longitudinal momentum fraction x{sub F} in the interval 0.1 < x{sub F} < 1.0, with {alpha} = 0.778 {+-} 0.014. The average value of {alpha} for charm production by pion beams is {alpha}{sub meson} = 0.850 {+-} 0.028. This is somewhat larger than the corresponding average {alpha}{sub baryon} = 0.755 {+-} 0.016 for charm production by baryon beams ({Sigma}{sup -} and protons).
Date: December 1, 2009
Creator: Blanco-Covarrubias, E.Alejandro & U., /San Luis Potosi
System: The UNT Digital Library
Search for the Higgs boson in the ZH->nunubb channel: Development of a b-tagging method based on soft muons (open access)

Search for the Higgs boson in the ZH->nunubb channel: Development of a b-tagging method based on soft muons

In the Standard Model of particle physics, the Higgs boson generates elementary particle masses. Current theoretical and experimental constraints lead to a Higgs boson mass between 114.4 and 158 GeV with 95% confidence level. Moreover, Tevatron has recently excluded the mass ranges between 100 and 109 GeV, 158 and 175 GeV with 95% confidence level. These results gives a clear indication to search for a Higgs boson at low mass. The D0 detector is located near Chicago, at the Tevatron, a proton-antiproton collider with an energy in the center of mass of 1.96 TeV. The topic of this thesis is the search for a Higgs boson in association with a Z boson. This channel is sensitive to low mass Higgs boson (<135 GeV) which has a branching ratio H {yields} bb varies between 50% and 90% in this mass range. The decay channel ZH {yields} {nu}{bar {nu}}b{bar b} studied has in the final state 2 heavy-flavor jets and some missing transverse energy due to escaping neutrinos. The heavy-flavor jets identification ('b-tagging') is done with a new algorithm (SLTNN) developped specifically for semi-leptonic decay of b quarks. The Higgs boson search analysis was performed with 3 fb{sup -1} of data. The …
Date: October 1, 2010
Creator: Jamin, David
System: The UNT Digital Library