8 Matching Results

Results open in a new window/tab.

Search for V H and Technicolor Producion in the qqbb Final State Using the RunII D0 Detector (open access)

Search for V H and Technicolor Producion in the qqbb Final State Using the RunII D0 Detector

A search for dijet resonance production in a four-jet all-hadronic final state from the D0 detector at Fermilab's Tevatron is presented. The data set, acquired at a p{bar p} center-of-mass energy of {radical}s = 1.96 TeV, contains primarily multijet events and represents approximately 1 fb{sup -1} of data. The cross section limits for associated Higgs production and Technicolor processes are determined through a background subtraction method using data to estimate the background. This four-jet channel is potentially very powerful, but is extremely challenging due to the large multijet background from QCD processes. Background rejection is performed by utilizing b-tagging, pre-selection cuts, a multi-variate boosted decision tree discriminant, and the correlated information contained in the M(bb) and M(jj) dijet invariant masses. The search for V H (WH+ZH) processes yields a 95% confidence level observed upper limit of 20.4 pb on the VH cross section for a Higgs mass of 115 GeV/c{sup 2}. Additionally, a 95% confidence level observed upper limit of 16.7 pb was set for a Higgs boson mass of 125 GeV/c{sup 2} and 24.6 pb was set for a Higgs boson mass of 135 GeV/c{sup 2}. The same data set was used to place limits on the Technicolor process …
Date: April 1, 2010
Creator: Clutter, Justace R.
System: The UNT Digital Library
MEASUREMENTS OF DIRECT CP VIOLATION AND CONSTRAINT ON THE CKM TRIANGLE IN B->K*pi DECAYS (open access)

MEASUREMENTS OF DIRECT CP VIOLATION AND CONSTRAINT ON THE CKM TRIANGLE IN B->K*pi DECAYS

We constrain the apex of the Cabibbo-Kobayashi-Maskawa unitarity triangle with measurements of B {yields} K*{pi} amplitudes from analyses of B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0} and B{sup 0} {yields} K{sub S}{pi}{sup +}{pi}{sup -} decays. This constraint is consistent with the world average. The B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0} decay mode is reconstructed from a sample of 454 million B{sup 0}{bar B}{sup 0} events collected by the BABAR detector at SLAC. We measure direct CP violation in B{sup 0} {yields} K*{sup +}{pi}{sup -} decays at the level of 3{sigma} when measurements from both B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0} and B{sup 0} {yields} K{sub S}{pi}{sup +}{pi}{sup -} decays are combined.
Date: April 29, 2010
Creator: Wagner, Andrew Phillips
System: The UNT Digital Library
A Measurement of Neutrino-Induced Charged-Current Neutral Pion Production (open access)

A Measurement of Neutrino-Induced Charged-Current Neutral Pion Production

This work presents the first comprehensive measurement of neutrino-induced charged-current neutral pion production (CC{pi}{sup 0}) off a nuclear target. The Mini Booster Neutrino Experiment (MiniBooNE) and Booster Neutrino Beam (BNB) are discussed in detail. MiniBooNE is a high-statistics ({approx} 1,000,000 interactions) low-energy (E{sub {nu}} {element_of} 0.5-2.0 GeV) neutrino experiment located at Fermilab. The method for selecting and reconstructing CC{pi}{sup 0} events is presented. The {pi}{sup 0} and {mu}{sup -} are fully reconstructed in the final state allowing for the measurement of, among other things, the neutrino energy. The total observable CC{pi}{sup 0} cross-section is presented as a function of neutrino energy, along with five differential cross-sections in terms of the final state kinematics and Q{sup 2}. The results are combined to yield a flux-averaged total cross-section of <{sigma}>{sub {Phi}} = (9.2 {+-} 0.3{sub stat.} {+-} 1.5{sub syst}.) x 10{sup -39} cm{sup 2}/CH{sub 2} at energy 965 MeV. These measurements will aid future neutrino experiments with the prediction of their neutrino interaction rates.
Date: April 1, 2010
Creator: Nelson, Robert H.
System: The UNT Digital Library
A search for $ZH\rightarrow \mu\mu b \bar{b}$ production at the Tevatron (open access)

A search for $ZH\rightarrow \mu\mu b \bar{b}$ production at the Tevatron

The Standard Model describes with a very good accuracy all interactions of the, so far, known elementary particles. However the Higgs mechanism, which gives rise to the observed mass of these particles, has not yet been confirmed. The Higgs particle has not yet been observed, and the observation or exclusion is an important test of the Standard Model. The Standard Model does not predict the mass of the Higgs particle, however it does impose some limits on the range in which this mass can lie. In direct searches a Higgs with a mass smaller than 114.4 GeV and within 162 GeV and 166 GeV has been excluded at 95% CL at the LEP and the Tevatron colliders. The analysis presented in this thesis is aimed to search for the ZH → μμb$\bar{b}$ events in 3.1 fb<sup>-1</sup> of data collected with the DØ detector in p$\bar{p}$ collisions at √s = 1.96 TeV.
Date: April 20, 2010
Creator: Ancu, Lucian-Stefan
System: The UNT Digital Library
Search for the Standard Model Higgs Boson in p anti-p Interactions with the Decay Mode H --> W+W- --> mu+nu mu-anti-nu at the D0 Experiment (open access)

Search for the Standard Model Higgs Boson in p anti-p Interactions with the Decay Mode H --> W+W- --> mu+nu mu-anti-nu at the D0 Experiment

A search for the standard model Higgs boson in p{bar p} collisions resulting in two muons and large missing transverse energy is presented. The analysis uses 4.2 fb{sup -1} of integrated luminosity at a center-of-mass energy of {radical}s = 1.96 TeV collected between April 2002 and December 2008 with the D0 detector at the Fermilab Tevatron collider. No significant excess above the background estimation is observed and limits are derived on Higgs boson production.
Date: April 1, 2010
Creator: Johnston, Dale Morgan & U., /Nebraska
System: The UNT Digital Library
Laser Intertial Fusion Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System (open access)

Laser Intertial Fusion Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System

This study investigates the neutronics design aspects of a hybrid fusion-fission energy system called the Laser Fusion-Fission Hybrid (LFFH). A LFFH combines current Laser Inertial Confinement fusion technology with that of advanced fission reactor technology to produce a system that eliminates many of the negative aspects of pure fusion or pure fission systems. When examining the LFFH energy mission, a significant portion of the United States and world energy production could be supplied by LFFH plants. The LFFH engine described utilizes a central fusion chamber surrounded by multiple layers of multiplying and moderating media. These layers, or blankets, include coolant plenums, a beryllium (Be) multiplier layer, a fertile fission blanket and a graphite-pebble reflector. Each layer is separated by perforated oxide dispersion strengthened (ODS) ferritic steel walls. The central fusion chamber is surrounded by an ODS ferritic steel first wall. The first wall is coated with 250-500 {micro}m of tungsten to mitigate x-ray damage. The first wall is cooled by Li{sub 17}Pb{sub 83} eutectic, chosen for its neutron multiplication and good heat transfer properties. The {sub 17}Pb{sub 83} flows in a jacket around the first wall to an extraction plenum. The main coolant injection plenum is immediately behind the Li{sub …
Date: April 8, 2010
Creator: Kramer, K
System: The UNT Digital Library
Electron Generation and Transport in Intense Relativistic Laser-Plasma Interactions Relevant to Fast Ignition ICF (open access)

Electron Generation and Transport in Intense Relativistic Laser-Plasma Interactions Relevant to Fast Ignition ICF

The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.
Date: April 21, 2010
Creator: Ma, T
System: The UNT Digital Library
Social Anxiety and Word Use: How Environments Can Influence Words (open access)

Social Anxiety and Word Use: How Environments Can Influence Words

This paper discusses research on social anxiety and word use.
Date: April 15, 2010
Creator: Morgan, Heather C. & Boals, Adriel
System: The UNT Digital Library