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Numerical and Experimental Investigations of a Rotating Heat Pipe (open access)

Numerical and Experimental Investigations of a Rotating Heat Pipe

None
Date: March 15, 2007
Creator: Jankowski, Todd A.
System: The UNT Digital Library
Measurement of the ratio of branching fractions b(bs --> ds- ds+) /b (b0 --> d- ds+) with the CDF detector (open access)

Measurement of the ratio of branching fractions b(bs --> ds- ds+) /b (b0 --> d- ds+) with the CDF detector

In this thesis they report the measurement of ratios of branching fractions: {Beta}(B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -})/{Beta}(B{sup 0} {yields} D{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -}), and {Beta}(B{sup 0} {yields} D{sup -}D{sub s}{sup +})/{Beta}(B{sup 0} {yields} D{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -}), using 355 pb{sup -1} of data collected by CDF detector at the Tevatron p{bar p} collider at {radical}s = 1.96 TeV.
Date: March 1, 2007
Creator: Iyutin, Boris
System: The UNT Digital Library
Cosmological Analysis From Large-Scale Anisotropic Correlation Function of the Sloan Digital Sky Survey (open access)

Cosmological Analysis From Large-Scale Anisotropic Correlation Function of the Sloan Digital Sky Survey

None
Date: March 1, 2008
Creator: Okumura, Teppei & U., /Nagoya
System: The UNT Digital Library
Measurement of the ttbar production cross section in the MET+jets channel at CDF (open access)

Measurement of the ttbar production cross section in the MET+jets channel at CDF

This thesis is focused on an inclusive search of the t{bar t} {yields} E{sub T} + jets decay channel by means of neural network tools in proton antiproton collisions at {radical}s = 1.96 TeV recorded by the Collider Detector at Fermilab (CDF). At the Tevatron p{bar p} collider top quarks are mainly produced in pairs through quark-antiquark annihilation and gluon-gluon fusion processes; in the Standard Model description, the top quark then decays to a W boson and a b quark almost 100% of the times, so that its decay signatures are classified according to the W decay modes. When only one W decays leptonically, the t{bar t} event typically contains a charged lepton, missing transverse energy due to the presence of a neutrino escaping from the detector, and four high transverse momentum jets, two of which originate from b quarks. In this thesis we describe a t{bar t} production cross section measurement which uses data collected by a 'multijet' trigger, and selects this kind of top decays by requiring a high-P{sub T} neutrino signature and by using an optimized neural network to discriminate top quark pair production from backgrounds. In Chapter 1, a brief review of the Standard Model of …
Date: March 1, 2008
Creator: Compostella, Gabriele & /INFN, Trento
System: The UNT Digital Library
Study on the top quark pair production mechanism in 1.96 TeV proton-antiproton collisions (open access)

Study on the top quark pair production mechanism in 1.96 TeV proton-antiproton collisions

The study of the top quark pair production mechanism in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV is described. The main subjects are the measurements of the top quark pair production cross section, the top quark mass and a search for a new particle decaying to the top quark pair. The analyses are based on 1.9 fb{sup -1} of data collected by the Collider Detector at Fermilab (CDF) Run II experiment between March 2002 and May 2007, using the lepton+jets events. The measured top quark pair production cross section is 8.2 {+-} 0.5 (stat.) {+-} 0.8 (syst.) {+-} 0.5 (lum.) pb, which is slightly higher than the standard model prediction at the top mass of 175 GeV/c{sup 2}. The top quark mass is an important parameter in the standard model, and also in the experimental studies. The measured top quark mass if 171.6 {+-} 2.0 (stat.) {+-} 1.3(syst.) GeV/c{sup 2}. Finally, they report on a search for a new gauge boson decaying to t{bar t}, which interferes with the standard model gluon in the q{bar q} {yields} t{bar t} production process. They call such a hypothetical particle a 'Massive Gluon'. The observed t{bar t} invariant mass distribution is …
Date: March 1, 2008
Creator: Naganoma, Junji & U., /Waseda
System: The UNT Digital Library
Measurement of CP Violation in B0 to Phi K0, and of Branching Fraction and CP Violation in B0 to F0(980) K0(S) (open access)

Measurement of CP Violation in B0 to Phi K0, and of Branching Fraction and CP Violation in B0 to F0(980) K0(S)

The authors measure the time-dependent CP asymmetry parameters in B{sup 0} {yields} K{sup +}K{sup -}K{sup 0} based on a data sample of approximately 277 million B-meson pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct two-body B{sup 0} decays to {phi}(1020)K{sub s}{sup 0} and {phi}(1020)K{sub L}{sup 0}. Using a time-dependent maximum-likelihood fit, they measure sin2{beta}{sub eff}({phi}K{sup 0}) = 0.48 {+-} 0.28 {+-} 0.10, and C({phi}K{sup 0}) = 0.16 {+-} 0.25 {+-} 0.09, where the first error is statistical, and the second is systematic. They also present measurements of the CP-violating asymmetries in the decay B{sup 0} {yields} f{sub 0}({yields} {pi}{sup +}{pi}{sup -})K{sub s}{sup 0}. The results are obtained from a data sample of 209 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays, also collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. From a time-dependent maximum-likelihood fit they measure the mixing-induced CP violation parameter S(f{sub 0}(980)K{sub S}{sup 0}) = - sin 2{beta}{sub eff}f{sub 0}(980)K{sub S}{sup 0} = -0.95{sub -0.23}{sup +0.32} {+-} 0.10 and the direct CP violation parameter C(f{sub 0}(980)K{sub S}{sup 0}) = - 0.24 {+-} 0.31 {+-} 0.15, where the first errors are statistical and …
Date: March 10, 2008
Creator: Kutter, Paul E.
System: The UNT Digital Library
Neutrino induced events in the MINOS detectors (open access)

Neutrino induced events in the MINOS detectors

The MINOS experiment is designed to study neutrino oscillations. It uses an accelerator generated beam of neutrinos and two detectors, the smaller at a distance of 1km and the larger at 735 km. By comparing the spectrum and flavour composition of the beam at the two detectors precise determinations of the oscillation parameters are possible. This thesis concentrates on the analysis of data from the larger Far Detector. By studying the spectrum of neutral current events it is possible to look for evidence of non-interacting 'sterile' neutrinos. The thesis describes how events are selected for this analysis, and a method for discriminating between charged current and neutral current events. The systematic uncertainties resulting from these cuts are evaluated. Several techniques for using Near Detector data to eliminate systematic uncertainties in the predicted Far Detector spectrum are compared. An oscillation analysis, based on the first year of MINOS data, uses the selected events to make a measurement of f{sub s}, the fraction of unseen neutrinos that are sterile. The measured value is f{sub s} = 0.07{sup +0.32} at 68%C.L., and is consistent with the standard three-neutrino picture, which has no sterile neutrino.
Date: March 1, 2008
Creator: Litchfield, Reuben Phillip
System: The UNT Digital Library
Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part II. Recovery of Ammonia from Sour Waters (open access)

Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part II. Recovery of Ammonia from Sour Waters

Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, SUCCiOlC acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility …
Date: March 1, 1990
Creator: Poole, L. J. & King, C. J.
System: The UNT Digital Library
Search for WW and WZ production in lepton, neutrino plus jets final states at CDF Run II and Silicon module production and detector control system for the ATLAS SemiConductor Tracker (open access)

Search for WW and WZ production in lepton, neutrino plus jets final states at CDF Run II and Silicon module production and detector control system for the ATLAS SemiConductor Tracker

In the first part of this work, we present a search for WW and WZ production in charged lepton, neutrino plus jets final states produced in p{bar p} collisions with {radical}s = 1.96 TeV at the Fermilab Tevatron, using 1.2 fb{sup -1} of data accumulated with the CDF II detector. This channel is yet to be observed in hadron colliders due to the large singleWplus jets background. However, this decay mode has a much larger branching fraction than the cleaner fully leptonic mode making it more sensitive to anomalous triple gauge couplings that manifest themselves at higher transverse W momentum. Because the final state is topologically similar to associated production of a Higgs boson with a W, the techniques developed in this analysis are also applicable in that search. An Artificial Neural Network has been used for the event selection optimization. The theoretical prediction for the cross section is {sigma}{sub WW/WZ}{sup theory} x Br(W {yields} {ell}{nu}; W/Z {yields} jj) = 2.09 {+-} 0.14 pb. They measured N{sub Signal} = 410 {+-} 212(stat) {+-} 102(sys) signal events that correspond to a cross section {sigma}{sub WW/WZ} x Br(W {yields} {ell}{nu}; W/Z {yields} jj) = 1.47 {+-} 0.77(stat) {+-} 0.38(sys) pb. The 95% …
Date: March 1, 2008
Creator: Sfyrla, Anna & U., /Geneva
System: The UNT Digital Library
Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts (open access)

Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts

Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, succinic acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility …
Date: March 1, 1990
Creator: Poole, L. J. & King, C. J.
System: The UNT Digital Library
CHARGE-EXCHANGE SCATTERING OF NEGATIVE PIONS BY HYDROGEN AT 230,260, 290, 317 AND 371 MeV (open access)

CHARGE-EXCHANGE SCATTERING OF NEGATIVE PIONS BY HYDROGEN AT 230,260, 290, 317 AND 371 MeV

The differential cross section for charge-exchange scattering of negative pions by hydrogen has been observed at 230, 260, 290, 317, and 371 Mev. The reaction was observed by detecting one gamma ray from the {pi}{sup 0} decay with a scintillation-counter telescope.
Date: March 18, 1960
Creator: Caris, John C
System: The UNT Digital Library
Top quark mass measurement (open access)

Top quark mass measurement

None
Date: March 1, 2008
Creator: Maki, Tuula & Tech., /Helsinki Inst. of Phys. /Helsinki U. of
System: The UNT Digital Library
Direct search for heavy neutral gauge bosons in the dielectron channel at D0 (open access)

Direct search for heavy neutral gauge bosons in the dielectron channel at D0

None
Date: March 1, 2008
Creator: Katsanos, Ioannis
System: The UNT Digital Library
Measurement of the Ratio of Branching Fractions Br(Bs -> Ds- pi+)/Br(B -> D- pi+) at CDF-II (open access)

Measurement of the Ratio of Branching Fractions Br(Bs -> Ds- pi+)/Br(B -> D- pi+) at CDF-II

The measurement of B{sub s}{sup 0} mixing is one of the flagship analyses for the Run II B physics program. The sensitivity of the measurement to the frequency of B{sub s}{sup 0} oscillations strongly depends on the number of reconstructed B{sub s}{sup 0} mesons. They present the measurement of the ratio of branching fractions Br(B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +})/Br(B{sup 0} {yields} D{sup -}{pi}{sup +}), which directly influences the number of B{sub s}{sup 0} events available for the measurement of B{sub s}{sup 0} mixing at CDF-II. They analyze 115 pb{sup -1} of data collected with the CDF-II detector in p{bar p} collisions at {radical}s = 1.96 TeV using a novel displaced track trigger. They reconstruct 78 {+-} 11 B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +} decays at 1153 {+-} 45 B{sup 0} {yields} D{sup -}{pi}{sup +} decays with good signal to background ratio. This is the world's largest sample of fully reconstructed B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +} decays. They find the ratio of production fractions multiplied by the ratio of branching fractions to be: f{sub s}/f{sub d} {center_dot} Br(B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +})/Br(B{sup 0} {yields} D{sup -}{pi}{sup +}) = 0.325 {+-} …
Date: March 1, 2004
Creator: Furic, Ivan Kresimir
System: The UNT Digital Library
Search for Lepton Flavour Violating Decays Tau -> l Ks with the BABAR Detector (open access)

Search for Lepton Flavour Violating Decays Tau -> l Ks with the BABAR Detector

We present the search for the lepton flavour violating decay {tau} {yields} lK{sup 0}{sub s} with the BaBar experiment data. This process and many other lepton flavour violating {tau} decays, like {tau} {yields} {mu}{gamma} and {tau} {yields} lll, are one of the most promising channel to search for evidence of new physics. According to the Standard Model and the neutrino mixing parameters, branching fractions are estimated well below 10{sup -14}, but many models of new physics allow for branching fractions values close to the present experimental sensitivity. This analysis is based on a data sample of 469fb{sup -1} collected by BABAR detector at the PEP-II storage ring from 1999 to 2007, equivalent to 431 millions of {tau} pairs. the BABAR experiment, initially designed for studying CP violation in B mesons, has demonstrated to be one of the most suitable environments for studying {tau} decays. The tracking system, the calorimeter and the particle identification of BABAR, together with the knowledge of the {tau} initial energy, allow an extremely powerful rejection of background events that, for this analysis, is better than 10{sup -9}. Being {tau} {yields} lK{sup 0}{sub s} a decay mode without neutrinos, the signal {tau} decay can be fully reconstructed. …
Date: March 20, 2009
Creator: Cenci, Riccardo
System: The UNT Digital Library
Precision Measurements of Tau Lepton Decays (open access)

Precision Measurements of Tau Lepton Decays

Using data collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV, the branching fractions {Beta}({tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}) = (8.83 {+-} 0.01 {+-} 0.13)%, {Beta}({tau}{sup -} {yields} K{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}) = (0.273 {+-} 0.002 {+-} 0.009)%, {Beta}({tau}{sup -} {yields} K{sup -}{pi}{sup -}K{sup +}{nu}{sub {tau}}) = (0.1346 {+-} 0.0010 {+-} 0.0036)%, and {Beta}({tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}}) = (1.58 {+-} 0.13 {+-} 0.12) x 10{sup -5} are measured where the uncertainties are statistical and systematic, respectively. The invariant mass distribution for the {tau}{sup -} {yields} {pi}{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}} {yields} K{sup -}{pi}{sup -}{pi}{sup +}{nu}{sub {tau}}, {tau}{sup -} {yields} K{sup -}{pi}{sup -}K{sup +}{nu}{sub {tau}} and {tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}} decays are unfolded to correct for detector effects. A measurement of {Beta}({tau}{sup -} {yields} {phi}{pi}{sup -}{nu}{sub {tau}}) = (3.42 {+-} 0.55 {+-} 0.25) x 10{sup -5}, a measurement of {Beta}({tau}{sup -} {yields} {phi}K{sup -}{nu}{sub {tau}}) = (3.39 {+-} 0.20 {+-} 0.28) x 10{sup -5} and an upper limit on {Beta}({tau}{sup -} {yields} K{sup -}K{sup -}K{sup +}{nu}{sub {tau}}[ex.{phi}]) {le} 2.5 x 10{sup -6} {at} 905 CL are determined from …
Date: March 16, 2010
Creator: Nugent, Ian M.
System: The UNT Digital Library
Simulation free measurement of the B+ lifetime using decays selected using displaced tracks (open access)

Simulation free measurement of the B+ lifetime using decays selected using displaced tracks

The lifetime of the B{sup {+-}} meson is measured using the decay channel B{sup +} {yields} {bar D}{sup 0}{pi}{sup +}. The measurement is made using approximately 1.0 fb{sup -1} of Tevatron proton-anti-proton collision data at {radical}s = 1.96 TeV collected by the CDF detector. The data were collected using impact parameter based triggers that were designed to select events with a secondary vertex. The trigger selection criteria result in data rich in a variety of B hadron decays, but intrinsically bias the lifetime distribution of the collected signal events. The traditional way to compensate for the bias is to use information from simulation. Presented here is a new method for correction of the lifetime bias using an analytical technique that uses information from the data only. This eliminates measurement uncertainty due to data and simulation agreement, ultimately resulting in a smaller systematic measurement uncertainty. The B{sup {+-}} lifetime measurement is the first measurement using this new technique and demonstrates its potential for use in future measurements. The B{sup {+-}} lifetime is measured to be {tau}(B{sup {+-}}) = 1.662 {+-} 0.023(stat) {+-} 0.015(syst)ps.
Date: March 1, 2009
Creator: Malde, Sneha
System: The UNT Digital Library
The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems (open access)

The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of …
Date: March 20, 2009
Creator: Guo, Jiquan
System: The UNT Digital Library
Measurement of the Oscillation Frequency of B_s Mesons in the Hadronic Decay Mode B_s-> pi D_s(phi pi)X$ with the D0 Detector at the Fermilab Tevatron Collider (open access)

Measurement of the Oscillation Frequency of B_s Mesons in the Hadronic Decay Mode B_s-> pi D_s(phi pi)X$ with the D0 Detector at the Fermilab Tevatron Collider

The standard model (SM) of particle physics is a theory, describing three out of four fundamental forces. In this model the Cabibbo-Kobayashi-Maskawa (CKM) matrix describes the transformation between the mass and weak eigenstates of quarks. The matrix properties can be visualized as triangles in the complex plane. A precise measurement of all triangle parameters can be used to verify the validity of the SM. The least precisely measured parameter of the triangle is related to the CKM element |V{sub td}|, accessible through the mixing frequency (oscillation) of neutral B mesons, where mixing is the transition of a neutral meson into its anti-particle and vice versa. It is possible to calculate the CKM element |V{sub td}| and a related element |V{sub ts}| by measuring the mass differences {Delta}m{sub d} ({Delta}m{sub s}) between neutral B{sub d} and {bar B}{sub d} (B{sub s} and {bar B}{sub s}) meson mass eigenstates. This measurement is accomplished by tagging the initial and final state of decaying B mesons and determining their lifetime. Currently the Fermilab Tevatron Collider (providing p{bar p} collisions at {radical}s = 1.96 TeV) is the only place, where B{sub s} oscillations can be studied. The first selection of the 'golden', fully hadronic decay …
Date: March 1, 2009
Creator: Weber, Gernot August & /Mainz U., Inst. Phys.
System: The UNT Digital Library
Neutrino and antineutrino inclusive charged-current cross section measurement with the MINOS near detector (open access)

Neutrino and antineutrino inclusive charged-current cross section measurement with the MINOS near detector

This thesis presents the measurement of energy dependence of the neutrino-nucleon inclusive charged current cross section on an isoscalar target in the range 3-50 GeV for neutrinos and 5-50 GeV energy range for antineutrinos. The data set was collected with the MINOS Near Detector using the wide band NuMI beam at Fermilab. The size of the charged current sample is 1.94 x 10{sup 6} neutrino events and 1.60 x 10{sup 5} antineutrino events. The flux has been extracted using a low hadronic energy sub-sample of the charged current events. The energy dependence of the cross section is obtained by dividing the charged current sample with the extracted flux. The neutrino and antineutrino cross section exhibits a linear dependence on energy at high energy but shows deviations from linear behavior at low energy. We also present a measurement of the ratio of antineutrino to neutrino inclusive cross section.
Date: March 1, 2009
Creator: Bhattacharya, Debdatta & U., /Pittsburgh
System: The UNT Digital Library
Measurement of the Single Top Quark Production Cross Section in 1.96-TeV Proton-Antiproton Collisions (open access)

Measurement of the Single Top Quark Production Cross Section in 1.96-TeV Proton-Antiproton Collisions

Top quarks are predominantly produced in pairs via the strong interaction in {bar p}p collisions at {radical}s = 1.96 TeV . The top quark has a weak isospin 1/2, composing a weak isospin doublet with the bottom quark. This characteristic predicts not only top quark pair production via strong interaction but also single production together with a bottom quark via weak interaction. However, finding single top quark production is challenging since it is rarely produced ({sigma}{sub singletop} = 2.9 pb) against background processes with the same final state like W+jets and t{bar t}. A measurement of electroweak single top production probes the W-t-b vertex, which provides a direct determination of the Cabbibo-Kobayashi-Maskawa (CKM) matrix element |V{sub tb}|. The sample offers a source of almost 100% polarized top quarks. This thesis describes an optimized search for s-channel single top quark production and a measurement of the single top production cross section using 2.7 fb{sup -1} of data accumulated with the CDF detector. We are using events with one high-p{sub T} lepton, large missing E{sub T} and two identified b-quark jets where one jet is identified using a secondary vertex tagger, called SecVtx, and the other jet is identified using SecVtx or …
Date: March 1, 2009
Creator: Nakamura, Koji
System: The UNT Digital Library
Measurement of the $WW+WZ$ production cross section in a semileptonic decay mode at CDF (open access)

Measurement of the $WW+WZ$ production cross section in a semileptonic decay mode at CDF

The measurement of the WW + WZ production cross section in a semileptonic decay mode is presented. The measurement is carried out with 4.6 fb{sup -1} of integrated luminosity collected by the CDF II detector in {radical}s = 1.96 TeV proton-antiproton collisions at the Tevatron. The main experimental challenge is identifying the signal in the overwhelming background from W+jets production. The modeling of the W+jets background is carefully studied and a matrix element technique is used to build a discriminant to separate signal and background. The cross section of WW + WZ production is measured to be {sigma}(p{bar p} {yields} WW + WZ) = 16.5{sub -3.0}{sup +3.3} pb, in agreement with the next-to-leading order theoretical prediction of 15.1 {+-} 0.9 pb. The significance of the signal is evaluated to be 5.4{sigma}. This measurement is an important milestone in the search for the Standard Model Higgs boson at the Tevatron.
Date: March 1, 2010
Creator: Hurwitz, Martina
System: The UNT Digital Library
A study of muon neutrino to electron neutrino oscillations in the MINOS experiment (open access)

A study of muon neutrino to electron neutrino oscillations in the MINOS experiment

The observation of neutrino oscillations (neutrino changing from one flavor to another) has provided compelling evidence that the neutrinos have non-zero masses and that leptons mix, which is not part of the original Standard Model of particle physics. The theoretical framework that describes neutrino oscillation involves two mass scales ({Delta}m{sub atm}{sup 2} and {Delta}m{sub sol}{sup 2}), three mixing angles ({theta}{sub 12}, {theta}{sub 23}, and {theta}{sub 13}) and one CP violating phase ({delta}{sub CP}). Both mass scales and two of the mixing angles ({theta}{sub 12} and {theta}{sub 23}) have been measured by many neutrino experiments. The mixing angle {theta}{sub 13}, which is believed to be very small, remains unknown. The current best limit on {theta}13 comes from the CHOOZ experiment: {theta}{sub 13} < 11{sup o} at 90% C.L. at the atmospheric mass scale. {delta}{sub CP} is also unknown today. MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino experiment based at Fermi National Accelerator Laboratory. The experiment uses a muon neutrino beam, which is measured 1 km downstream from its origin in the Near Detector at Fermilab and then 735 km later in the Far Detector at the Soudan mine. By comparing these two measurements, MINOS can obtain …
Date: March 1, 2009
Creator: Yang, Tingjun
System: The UNT Digital Library
First evidence for WW and WZ diboson production with semi-leptonic decays at a Hadron Collider (open access)

First evidence for WW and WZ diboson production with semi-leptonic decays at a Hadron Collider

Presented is a measurement of the simultaneous production of a W{sup {+-}} boson in association with a second weak boson (W{sup {+-}} or Z{sup 0}) in p{bar p} collisions at {radical}s = 1.96 TeV. Events are consider with one electron or one muon, missing transverse energy, and at least two hadronic jets. The data were collected by the D0 detector in Run IIa of the Tevatron accelerator and correspond to 1.07 fb{sup -1} of integrated luminosity for each of the two channels (WW/WZ {yields} e{nu}q{bar q} and WW/WZ {yields} {mu}{nu}q{bar q}). The cross section for WW + WZ production is measured to be 20.2 {+-} 2.5(stat) {+-} 3.6(sys) {+-} 1.2(lum) pb with a Gaussian significance of 4.4 standard deviations above the background-only scenario. This measurement is consistent with the Standard Model prediction and represents the first direct evidence for WW and WZ production with semi-leptonic decays at a hadron collider.
Date: March 1, 2009
Creator: Haley, Joseph Glenn Biddle
System: The UNT Digital Library