Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry (open access)

Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 {micro}g L{sup -1} or better were found for P, Mn, Fe, Cu, and Zn in a 60 {micro}L injection in a physiological saline matrix.
Date: August 18, 2008
Creator: Saetveit, Nathan Joe
System: The UNT Digital Library
Quantum Dynamical Behaviour in Complex Systems - A Semiclassical Approach (open access)

Quantum Dynamical Behaviour in Complex Systems - A Semiclassical Approach

One of the biggest challenges in Chemical Dynamics is describing the behavior of complex systems accurately. Classical MD simulations have evolved to a point where calculations involving thousands of atoms are routinely carried out. Capturing coherence, tunneling and other such quantum effects for these systems, however, has proven considerably harder. Semiclassical methods such as the Initial Value Representation (SC-IVR) provide a practical way to include quantum effects while still utilizing only classical trajectory information. For smaller systems, this method has been proven to be most effective, encouraging the hope that it can be extended to deal with a large number of degrees of freedom. Several variations upon the original idea of the SCIVR have been developed to help make these larger calculations more tractable; these range from the simplest, classical limit form, the Linearized IVR (LSC-IVR) to the quantum limit form, the Exact Forward-Backward version (EFB-IVR). In this thesis a method to tune between these limits is described which allows us to choose exactly which degrees of freedom we wish to treat in a more quantum mechanical fashion and to what extent. This formulation is called the Tuning IVR (TIVR). We further describe methodology being developed to evaluate the prefactor …
Date: May 22, 2008
Creator: Gliebe, Cheryn E & Ananth, Nandini
System: The UNT Digital Library
The Study of Electromagnetic Wave Propogation in Photonic Crystals Via Planewave Based Transfer (Scattering) Matrix Method with Active Gain Material Applications (open access)

The Study of Electromagnetic Wave Propogation in Photonic Crystals Via Planewave Based Transfer (Scattering) Matrix Method with Active Gain Material Applications

In this dissertation, a set of numerical simulation tools are developed under previous work to efficiently and accurately study one-dimensional (1D), two-dimensional(2D), 2D slab and three-dimensional (3D) photonic crystal structures and their defects effects by means of spectrum (transmission, reflection, absorption), band structure (dispersion relation), and electric and/or magnetic fields distribution (mode profiles). Furthermore, the lasing property and spontaneous emission behaviors are studied when active gain materials are presented in the photonic crystal structures. Various physical properties such as resonant cavity quality factor, waveguide loss, propagation group velocity of electromagnetic wave and light-current curve (for lasing devices) can be obtained from the developed software package.
Date: December 1, 2007
Creator: LI, Ming
System: The UNT Digital Library
The Differential cross section distribution of Drell-Yan dielectron pairs in the z boson mass region (open access)

The Differential cross section distribution of Drell-Yan dielectron pairs in the z boson mass region

We report on a measurement of the rapidity distribution, d{sigma}/dy, for Z=Drell-Yan {yields} ee events produced in p{bar p} collisions at {radical}s = 1.96 TeV. The data sample consists of 2.13 fb{sup -1} corresponding to about 160,000 Z/Drell-Yan {yields} ee candidates in the Z boson mass region collected by the Collider Detector at Fermilab. The d{sigma}/dy distribution, which is measured over the full kinematic range for e{sup +}e{sup -} pairs in the invariant mass range 66 < M{sub ee} < 116 GeV/c{sup 2}, is compared with theory predictions. There is good agreement between the data and predictions of Quantum Chromodynamics in Next to Leading Order with the CTEQ6.1M Parton Distribution Functions.
Date: November 1, 2008
Creator: Han, Jiyeon
System: The UNT Digital Library
Study of B_s Mixing at the D-Zero Detector at Fermilab Using the Semi-leptonic Decay B_s -> D_s mu nu X (open access)

Study of B_s Mixing at the D-Zero Detector at Fermilab Using the Semi-leptonic Decay B_s -> D_s mu nu X

B{sub s}{sup 0} mixing studies provide a precision test of Charge-Parity violation in the Standard Model. A measurement of {Delta}m{sub s} constrains elements of the CKM quark rotation matrix [1], providing a probe of Standard Model Charge-Parity violation. This thesis describes a study of B{sub s}{sup 0} mixing in the semileptonic decay B{sub s}{sup 0} {yields} D{sub s}{sup -} {mu}{sup +}{nu}X, where D{sub s}{sup -} {yields} {phi}{pi}{sup -}, using data collected at the D-Zero detector at Fermi National Accelerator in Batavia, Illinois. Approximately 2.8 fb{sup -1} of data collected between April 2002 and August 2007 was used, covering the entirety of the Tevatron's RunIIa (April 2002 to March 2006) and part of RunIIb (March 2006-August 2007). Taggers using both opposite-side and same-side information were used to obtain the flavor information of the B{sub s}{sup 0} meson at production. The charge of the muon in the decay B{sub s}{sup 0} {yields} D{sub s}{sup -}{mu}{sup +}{nu}X was used to determine the flavor of the B{sub s}{sup 0} at decay. The B{sub d}{sup 0} mixing frequency, {Delta}m{sub d}, was measured to verify the analysis procedure. A log-likelihood calculation was performed, and a measurement of {Delta}m{sub s} was obtained. The final result was {Delta}m{sub …
Date: June 1, 2008
Creator: Anzelc, Meghan
System: The UNT Digital Library
A Meaurement of the W+- production cross section in p anti-p collisions at sqroot(s)=1.96 TeV in the DiLepton channel and limits on anomalous WWZ/gamma couplings (open access)

A Meaurement of the W+- production cross section in p anti-p collisions at sqroot(s)=1.96 TeV in the DiLepton channel and limits on anomalous WWZ/gamma couplings

Measurements of the production cross section of W{sup +}W{sup -} pairs in p{bar p} collisions at 1.96 TeV and limits on trilinear gauge boson coupling (TGC) parameters are presented. The data were recorded with the CDF experiment at Tevatron during the 2001 and 2002 data taking periods in which a total integrated luminosity of 184 pb{sup -1} was collected. The data sample was filtered for events with two leptonic w boson decays where the charged leptons can be either electrons or muons. 17 events are observed against an expected background of 5.0{sub -0.8}{sup +2.2} events. The resulting cross-section is found to be {sigma}(p{bar p} {yields} W{sup +}W{sup -}) = 14.5{sub -5.1}{sup +5.8}(stat){sub -3.0}{sup +1.8}(syst) {+-} 0.9(lum) pb and agrees well with the Standard Model expectation. Limits on the TGC parameters {Delta}{kappa} and {lambda} are set under both the equal coupling scheme, that assumes the W boson couples identically to the Z and {gamma}, and the HISZ coupling scheme, that requires the couplings to respect SU(2){sub L} x &(1){sub Y} gauge symmetry. In both cases this is achieved by using a likelihood fit to the lepton-P{sub T} distribution of the 17 candidate events. The resulting limits are found to be: -0.4 …
Date: December 1, 2005
Creator: McGivern, Dustin & London, /University Coll.
System: The UNT Digital Library
QCD fits to neutrino-iron structure functions at NuTeV (open access)

QCD fits to neutrino-iron structure functions at NuTeV

This thesis presents a new determination of {Lambda}{sub QCD} from Next-to-Leading Order QCD fits to the Q{sup 2} dependence of neutrino-iron structure functions. This is the first measurement of {Lambda}{sub QCD} which uses a theoretical model that fully accounts for heavy quark production. Compared with previous neutrino measurements, the result has improved understanding of the largest systematic uncertainties on the muon and hadron energy scales. These improvements lead to one of the most precise determination of {alpha}{sub S} at moderate Q{sup 2}. NuTeV is a neutrino-iron deep inelastic scattering (DIS) experiment that collected data during 1996-97 at Fermilab. The key features of NuTeV include its sign-selected beam which produced separate high purity neutrino and antineutrino beams, and its continuous calibration beam which enabled NuTeV to considerably improve the knowledge of energy scales which have dominated uncertainties in the previous measurements.
Date: August 1, 2006
Creator: Radescu, Voica A. & U., /Pittsburgh
System: The UNT Digital Library
Error-Induced Beam Degradation in Fermilab's Accelerators (open access)

Error-Induced Beam Degradation in Fermilab's Accelerators

In Part I, three independent models of Fermilab's Booster synchrotron are presented. All three models are constructed to investigate and explore the effects of unavoidable machine errors on a proton beam under the influence of space-charge effects. The first is a stochastic noise model. Electric current fluctuations arising from power supplies are ubiquitous and unavoidable and are a source of instabilities in accelerators of all types. A new noise module for generating the Ornstein-Uhlenbeck (O-U) stochastic noise is first created and incorporated into the existing Object-oriented Ring Beam Injection and Tracking (ORBIT-FNAL) package. After being convinced with a preliminary model that the noise, particularly non-white noise, does matter to beam quality, we proceeded to measure directly current ripples and common-mode voltages from all four Gradient Magnet Power Supplies (GMPS). Then, the current signals are Fourier-analyzed. Based upon the power spectra of current signals, we tune up the Ornstein-Uhlnbeck noise model. As a result, we are able to closely match the frequency spectra between current measurements and the modeled O-U stochastic noise. The stochastic noise modeled upon measurements is applied to the Booster beam in the presence of the full space-charge effects. This noise model, accompanied by a suite of beam …
Date: August 1, 2007
Creator: Yoon, Phil S.
System: The UNT Digital Library
Search for High-Mass Resonances Decaying into Leptons of Different Flavor (e mu, e tau, mu tau) in p anti-p Collisions at sqrt(s) = 1.96 TeV (open access)

Search for High-Mass Resonances Decaying into Leptons of Different Flavor (e mu, e tau, mu tau) in p anti-p Collisions at sqrt(s) = 1.96 TeV

We present a search for high-mass resonances decaying into two leptons of different flavor: e{mu}, e{tau}, and {mu}{tau}. These resonances are predicted by several models beyond the standard model, such as the R-parity-violating MSSM. The search is based on 1 fb{sup -1} of data collected at the Collider Detector at Fermilab (CDF II) in proton anti-proton collisions. Our observations are consistent with the standard model expectations. The results are interpreted to set 95% C.L. upper limits on {sigma} x BR of {tilde {nu}}{sub {tau}} {yields} e{mu}, e{tau}, {mu}{tau}.
Date: October 1, 2008
Creator: Tu, Yanjun
System: The UNT Digital Library
Measurement of the inclusive jet cross section in proton-antiproton collisions at the center-of-mass energy of 1.96 TeV (open access)

Measurement of the inclusive jet cross section in proton-antiproton collisions at the center-of-mass energy of 1.96 TeV

This thesis studies the high-energy collisions of protons and antiprotons. The data used in the measurement were collected during 2004-2005 with the D0 detector at the Tevatron Collider of the Fermi National Accelerator Laboratory and correspond to 0.7 fb{sup -1} of integrated luminosity. High energy hadron collisions usually produce collimated sprays of particles called jets. The energy of the jets is measured using a liquid Argon-Uranium calorimeter and the production angle is determined with the help of silicon microstrip and scintillating fiber trackers. The inclusive jet cross section in proton-antiproton collisions is measured as a function of jet transverse momentum p{sub T} in six bins of jet rapidity at the center-of-mass energy {radical}s = 1.96 TeV. The measurement covers jet transerve momenta from 50 GeV up to 600 GeV and jet rapidities up to |y| = 2.4. The data are collected using a set of seven single jet triggers. Event and jet cuts are applied to remove non-physical backgrounds and cosmic-ray interactions. The data are corrected for jet energy calibration, cut and trigger efficiencies and finite jet p{sub T} resolution. The corrections are determined from data and the methods are tested with Monte Carlo simulation. The main experimental challenges in …
Date: July 1, 2008
Creator: Voutilainen, Mikko Antero & /Saclay, /Helsinki Inst. of Phys. /Helsinki U. of Tech. /Nebraska U.
System: The UNT Digital Library
Implementation of an interactive matching scheme for the Kapchinskij-Vladimirskij equations in the WARP code (open access)

Implementation of an interactive matching scheme for the Kapchinskij-Vladimirskij equations in the WARP code

The WARP code is a robust electrostatic particle-in-cell simulation package used to model charged particle beams with strong space-charge forces. A fundamental operation associated with seeding detailed simulations of a beam transport channel is to generate initial conditions where the beam distribution is matched to the structure of a periodic focusing lattice. This is done by solving for periodic, matched solutions to a coupled set of ODEs called the Kapchinskij-Vladimirskij (KV) envelope equations, which describe the evolution of low-order beam moments subject to applied lattice focusing, space-charge defocusing, and thermal defocusing forces. Recently, an iterative numerical method was developed (Lund, Chilton, and Lee, Efficient computation of matched solutions to the KV envelope equations for periodic focusing lattices, Physical Review Special Topics-Accelerators and Beams 9, 064201 2006) to generate matching conditions in a highly flexible, convergent, and fail-safe manner. This method is extended and implemented in the WARP code as a Python package to vastly ease the setup of detailed simulations. In particular, the Python package accommodates any linear applied lattice focusing functions without skew coupling, and a more general set of beam parameter specifications than its predecessor. Lattice strength iteration tools were added to facilitate the implementation of problems with …
Date: April 15, 2008
Creator: Chilton, Sven H.
System: The UNT Digital Library
Measurement of the W boson helicity in top quark decays (open access)

Measurement of the W boson helicity in top quark decays

A measurement of the fraction, f{sup +}, of right-handed W bosons produced in top quark decays is presented. This analysis is based on a sample corresponding to an integrated luminosity of 370 pb{sup -1}, collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider at {radical}s = 1.96 TeV. The helicity angle, {theta}*, is reconstructed for each lepton. f{sup +} is determined by comparing the cos {theta}* distribution from the data with that for the expected background and signal for various values of f{sup +}. The fraction of longitudinal W bosons, f{sup 0}, is assumed to be 0.7 as predicted by the standard model. This yields f{sup +} = 0.109 {+-} 0.094 (stat) {+-} 0.063 (syst), consistent with the standard model prediction of f{sup +} = 3.6x 10{sup -4}. The possibility that both f{sup +} and f{sup 0} stray from standard model values is also investigated. In this case cos {theta}* distributions for each possible W helicity state, along with the backgrounds, are fit to the cos {theta}* distribution for the data. The best fit values are f{sup +} = 0.82 {+-} 0.30(stat) and f{sup 0} = -0.58 {+-} 0.50(stat).
Date: August 1, 2007
Creator: Gmyrek, Bryan David
System: The UNT Digital Library
WW production cross section measurement and limits on anomalous trilinear gauge couplings at sqrt(s) = 1.96-TeV (open access)

WW production cross section measurement and limits on anomalous trilinear gauge couplings at sqrt(s) = 1.96-TeV

The cross section for WW production is measured and limits on anomalous WW{gamma} and WWZ trilinear gauge couplings are set using WW {yields} ee/e{mu}/{mu}{mu} events collected by the Run II D0 detector at the Fermilab Tevatron Collider corresponding to 1 fb{sup -1} of integrated luminosity at {radical}s = 1.96 TeV. Across the three final states, 108 candidate events are observed with 40.8 {+-} 3.8 total background expected, consistent with {sigma}(p{bar p} {yields} WW) = 11.6 {+-} 1.8(stat) {+-} 0.7(syst) {+-} 0.7(lumi) pb. Using a set of SU(2){sub L} {direct_product} U(1){sub Y} conserving constraints, the one-dimensional 95% C.L. limits on trilinear gauge couplings are -0.63 < {Delta}{kappa}{sub {gamma}} < 0.99, -0.15 < {lambda}{sub {gamma}} < 0.19, and -0.14 < {Delta}g{sub 1}{sup Z} < 0.34.
Date: April 1, 2008
Creator: Cooke, Michael P. & U., /Rice
System: The UNT Digital Library
Inclusive Rates and Spectra of the Lambda, Cascade, and Omega Hyperons atBaBar (open access)

Inclusive Rates and Spectra of the Lambda, Cascade, and Omega Hyperons atBaBar

We employ Runs 1-4 off-peak data sample (about 21.5 fb{sup -1}) to produce the current world-best spectra and production rates measurements for three strangely-flavored baryons: the {Lambda} hyperon, the cascade hyperon, and the {Omega} hyperon. These improved measurements shall enable theoretical and phenomelogical workers to generate more realistic models for the hadronization process, currently one of the unresolved problem areas in the standard model of particle physics. This analysis was conducted using codes from release 16 series. We report the production rate at 10.54 GeV for the {Lambda} as 0.0900 {+-} 0.0006(stat.) {+-} 0.0039(sys.) per hadronic event. Our measured production rate at the same energy for the cascade hyperon is 0.00562 {+-} 0.00013(stat.) {+-} 0.00045(sys.) per hadronic event, while that for the {Omega} hyperon is 0.00027 {+-} 0.00004(stat.) {+-} 0.0008(sys.) per hadronic event. The spectral measurements for the respective particles also constitute current world-best measurements.
Date: May 19, 2008
Creator: Chien, Andrew L.
System: The UNT Digital Library
A Search for Direct CP Violation in Two-Body Cabibbo-Suppressed Decays of Neutral Charmed Mesons (open access)

A Search for Direct CP Violation in Two-Body Cabibbo-Suppressed Decays of Neutral Charmed Mesons

Presented are the results of a search for direct CP violation in Cabibbo-suppressed decays of D{sup 0} to two charged daughters. The analysis described was performed on {approx}230 fb{sup -1} of the BABAR data sample, recorded at the Stanford Linear Accelerator Center and using the PEP-II electron storage rings. We measure CP asymmetries for decay to the KK and {pi}{pi} final states, as well as for the branching ratio, and develop a new technique for tagging-efficiency correction using the Cabibbo-favored K{pi} final state. We find some evidence for CP violation in decays to the KK final state and results that suggest CP violation in the {pi}{pi} final state as well.
Date: November 12, 2007
Creator: Flacco, Christian Julienne & /UC, Santa Cruz
System: The UNT Digital Library
Habilitation Thesis on STT and Higgs searches in WH Rroduction (open access)

Habilitation Thesis on STT and Higgs searches in WH Rroduction

The detector of the D0 experiment at the proton anti-proton collider Tevatron in Run II is discussed in detail. The performance of the collider and the experiment is presented. Standard model Higgs searches with integrated luminosities between 260 pb{sup -1} and 950 pb{sup -1} and their combination are performed. No deviation from SM background expectation has been observed. Sensitivity prospects at the Tevatron are shown.
Date: December 1, 2006
Creator: Sonnenschein, Lars
System: The UNT Digital Library
Search for neutral Higgs bosons decaying to tau pairs produced in association with b-quarks at s**(1/2)=1.96 TeV (open access)

Search for neutral Higgs bosons decaying to tau pairs produced in association with b-quarks at s**(1/2)=1.96 TeV

We report results from a search for neutral Higgs bosons decaying to tau pairs produced in association with a b-quark in 1.6 fb{sup -1} of data taken from June 2006 to March 2008 with the D0 detector at Fermi National Accelerator Laboratory. The final state includes a muon, hadronically decaying tau, and jet identified as coming from a b-quark. We set cross section times branching ratio limits on production of such neutral Higgs bosons {phi} in the mass range from 90 GeV to 160 GeV. Exclusion limits are set at the 95% Confidence Level for several supersymmetric scenarios.
Date: December 1, 2008
Creator: Herner, Kenneth Richard
System: The UNT Digital Library
Measurement of Pi-K Ratios from the NuMI Target (open access)

Measurement of Pi-K Ratios from the NuMI Target

Interactions of protons (p) with the NuMI (Neutrinos at the Main Injector) target are used to create the neutrino beam for the MINOS (Main Injector Neutrino Oscillation Search) Experiment. Using the MIPP (Main Injector Particle Production) experimental apparatus, the production of charged pions and kaons in p+NuMI interactions is studied. The data come from a sample of 2 x 10{sup 6} events obtained by MIPP using the 120 GeV/c proton beam from the Main Injector at Fermi National Accelerator Laboratory in Illinois, USA. Pions and kaons are identified by measurement in a Ring Imaging Cherenkov detector. Presented are measurements of {pi}{sup -}/{pi}{sup +}, K{sup -}/K{sup +}, {pi}{sup +}/K{sup +} and {pi}{sup -}/K{sup -} production ratios in the momentum range p{sub T} < 2 GeV/c transversely and 20 GeV/c < p{sub z} < 90 GeV/c longitudinally. Also provided are detailed comparisons of the MIPP NuMI data with the MIPP Thin Carbon data, the MIPP Monte Carlo simulation and the current MINOS models in the relevant momentum ranges.
Date: July 1, 2007
Creator: Seun, Sin Man & U., /Harvard
System: The UNT Digital Library
Measurement of the Production Cross Section of Top Quark Pairs in the Lepton + Jets Channel at d0 and Atlas and Interpretation in Terms of Charged Higgs Boson at Atlas (open access)
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
Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology (open access)

Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology

This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was found that instrument interface design also plays a critical role in the cluster ion distribution seen in the mass spectrum. In Chapter 5, ESI-MS was used to investigate toxic metal binding to the [Gln{sup 11}]-amyloid {beta}-protein fragment (1-16). Pb and Cd bound stronger than Zn, even in the presence of excess Zn. Hg bound weaker than Zn. There are endless options for future work on cluster ions. Any molecule that is poorly ionized in positive ion mode can potentially show an increase in ionization efficiency if an appropriate anion is used to produce a net negative charge. It is possible that drug protein or drug/DNA complexes can also be stabilized by adding counter-ions. This would preserve the solution characteristics of the complex in the gas phase. Once in …
Date: December 1, 2007
Creator: Lentz, Nicholas B.
System: The UNT Digital Library
Search for Higgs bosons decaying into tau pairs in ppbar collisions at D0 (open access)

Search for Higgs bosons decaying into tau pairs in ppbar collisions at D0

A search for neutral Higgs bosons decaying into tau pairs is presented using data in p{bar p} collisions at {radical}s = 1.96 TeV. One of the tau leptons is identified via its decay into an electron or muon and the other via its decay into a hadronic final state. The data, corresponding to an integrated luminosity of around 1.0 fb{sup -1}, were collected with the D0 detector at the Fermilab Tevatron collider between April 2002 and February 2006. No significant excess of events above the background expectation is observed and limits on the cross section times branching ratio for neutral Higgs bosons decaying into tau pairs, p{bar p} {yields} {phi} {yields} {tau}{sup +}{tau}{sup -}, are set. The cross section limits are interpreted as exclusions in the parameter space of the minimal supersymmetric Standard Model, resulting in exclusions in the range 40 < tan{beta} < 70 for M{sub A} < 200 GeV. Finally, the effect of Higgs bosons with a large total width is considered and the first model independent correction to the cross section limits for the width effect is presented.
Date: August 1, 2008
Creator: Owen, Mark A.
System: The UNT Digital Library
Search for Higgs boson production in proton-antiproton collisions at s**(1/2) = 1.96 TeV (open access)

Search for Higgs boson production in proton-antiproton collisions at s**(1/2) = 1.96 TeV

We performed a search for Standard Model Higgs boson production in association with W boson (p{bar p} {yields} W{sup {+-}}H {yields} {ell}{nu}b{bar b}) in p{bar p} collisions at {radical}s = 1.96 TeV. The search uses the data collected between February 2002 and February 2006 at Collider Detector at Fermilab (CDF), which corresponds to an integrated luminosity of about 1 fb{sup -1}. The experimental final state of WH {yields} {ell}{nu}b{bar b} process is lepton (e{sup {+-}}/{mu}{sup {+-}}), missing transverse energy and two jets. The largest background in lepton+jets events is W+light flavor process, therefore the identification of jets as b-jets reduces this kind of background significantly. We used displaced SECondary VerTeX b-tagging (SECVTX) technique, which utilizes the signature that b-jets have secondary vertex displaced away from primary vertex because of the long life time of B-mesons. However, there is still much contamination in SECVTX b-tagged jets. Finite resolution of secondary vertex tracking measurements results in false tags, and c-jets are also identified as b-jets due to the long life time of D-mesons frequently. For the purpose of increasing the purity of the SECVTX b-tagged jets, we applied Neural Network to SECVTX tagged jets for the first time by using secondary vertex …
Date: December 1, 2006
Creator: Kusakabe, Yoshiaki & U., /Waseda
System: The UNT Digital Library
Search for B to rho/omega gamma decays at BaBar (open access)

Search for B to rho/omega gamma decays at BaBar

The authors present the results of the search for the decays B{sup 0/{+-}} {yields} {rho}{sup 0/{+-}}{gamma} (previously observed) and B{sup 0} {yields} {omega}{gamma} (for which currently only an upper limit exists). Together with B {yields} K*{gamma} decays, B {yields} ({rho}/{omega}){gamma} allow us to measure the ratio of CKM-matrix elements |V{sub td}/V{sub ts}|. The analysis is based on the full BABAR dataset of 424.35 fb{sup -1} corresponding to 465 million B{bar B} pairs, and makes heavy use of multivariate classification techniques based on decision trees. They find {Beta}(B{sup {+-}} {yields} {rho}{sup {+-}}{gamma}) = (1.20{sub -0.38}{sup +0.42} {+-} 0.20) x 10{sup -6}, {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) = (0.95{sub -0.21}{sup +0.23} {+-} 0.06) x 10{sup -6}, {Beta}(B{sup 0} {yields} {omega}{gamma}) = (0.51{sub -0.24}{sup +0.27} {+-} 0.10) x 10{sup -6}, where the first error is statistical and the second is systematic. They do not observe a statistically significant signal in the latter channel and set an upper limit at {Beta}(B{sup 0} {yields} {omega}{gamma}) < 0.9 x 10{sup -6} (90% C.L.). They also measure the isospin and SU(3){sub F} violating quantities {Lambda}(B{sup +} {yields} {rho}{sup +}{gamma})/2{Lambda}(B{sup 0} {yields} {rho}{sup 0}{gamma})-1 = -0.43{sub -0.22}{sup +0.25} {+-} 0.10 and {Lambda}(B{sup 0} {yields} {omega}{gamma})/{Lambda}(B{sup 0} {yields} {rho}{sup …
Date: September 23, 2008
Creator: Piatenko, Timofei & /SLAC, /Caltech
System: The UNT Digital Library