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Iowa State University

Elementary Particles and Fields and String Theory

High energy physics

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Full-Text Articles in Physics

Search For A Neutral Technicolor Signature In Pp̄ Collisions At [Square Root Of S] = 18 Tev , Jesse Andrew Green Jan 2001

Search For A Neutral Technicolor Signature In Pp̄ Collisions At [Square Root Of S] = 18 Tev , Jesse Andrew Green

Retrospective Theses and Dissertations

The standard model (SM) of particle physics has been a very successful theory for decades; however, several features remain unexplained. One such feature is the mechanism of electro-weak symmetry-breaking. The Higgs mechanism is postulated as part of the SM to give us the masses of the W +/- and the Z0 bosons in a manner consistent with unitarity. The Higgs boson is a consequence of the mechanism currently used. It is massive, and has the quantum numbers of the vacuum; i.e. it is a scalar. Also, the pattern of fermion (quark and lepton) masses is yet to be understood. Technicolor ...


Search For An Msugra Signature In The Electron + Jets + [Missing Transverse Energy] Final State In [Proton-Antiproton] Collisions At [Square Root Of S] = 1.8 Tev , Zhang Zhou Jan 2001

Search For An Msugra Signature In The Electron + Jets + [Missing Transverse Energy] Final State In [Proton-Antiproton] Collisions At [Square Root Of S] = 1.8 Tev , Zhang Zhou

Retrospective Theses and Dissertations

We describe a search for a Minimal Supergravity (mSUGRA) signature in Run 1 data taken by the DO detector at the Fermilab Tevatron from 1995--1996. The total data luminosity is 92.7 pb-1. The data were examined for events with a single electron, four or more jets and large missing transverse energy. The major backgrounds are from W+jets, QCD, tt[macron], and WW events. We observed no excess of events in our data. Based on the data and the expected signal rate we obtain new limits on new physics in terms of mSUGRA model parameters.


Studies Of The Inclusive Semileptonic Decays Of The B-Hadrons , Jong Il Yi Jan 2000

Studies Of The Inclusive Semileptonic Decays Of The B-Hadrons , Jong Il Yi

Retrospective Theses and Dissertations

A detailed description of a new analysis, in which the correlation of the electric charge of the b-quark to that of the lepton is utilized to isolate different decay modes of the b-hadrons, is presented. Using the data collected by the DELPHI detector during the 1994 and 1995 data-taking periods, the inclusive b-hadron semileptonic branching fraction is measured to be B R b→ℓ % =10.75+/-0.15stat +/-0.28syst -0.24+0.43model . Along with the semileptonic branching fraction, the branching fractions for the cascade mode, b→c→ℓ , and the upper-vertex mode, b→c&d1;→ℓ , are also measured: BR b→c ...


Resonance Production In Quark And Gluon Jets , Derek William Lane Jan 1999

Resonance Production In Quark And Gluon Jets , Derek William Lane

Retrospective Theses and Dissertations

The formation of hadrons from free quarks and gluons is poorly understood and can not be fully explained by current theories. This hadronization process is described using phenomenological models, each reflecting possible scenarios for the QCD dynamics. Electron-positron annihilation at the Z0 resonance provides an ideal environment in which to study hadron production because of the combination of high event rates and clean final states due to the absence of beam and target remnants. Using the particle identification capabilities of the DELPHI detector at the Large Electron-Positron collider (LEP), it is possible to differentiate the production of different hadron species ...


Hard Single Diffraction In Pp̄ Collisions At 1800 And 630 Gev Center Of Mass Energies , Kristal Monika Mauritz Jan 1999

Hard Single Diffraction In Pp̄ Collisions At 1800 And 630 Gev Center Of Mass Energies , Kristal Monika Mauritz

Retrospective Theses and Dissertations

A search for evidence of Hard Single Diffraction (HSD) in forward and central jet systems is described for center-of-mass energies of 1800 and 630 GeV. Events are examined for the presence of a forward rapidity gap with concurrent jet production. Relative event rates are estimated for both processes as compared to an inclusive dijet data sample, and the distributions of Pomeron x in the proton, called xi, are also measured for both forward and central HSD events, The data measurements are compared to the Ingelman-Schlein model.


Flavor Changing Chronomagnetic Moments: A Monte Carlo Study Of The Top Quark , Matthias Danniel Hosch Jan 1998

Flavor Changing Chronomagnetic Moments: A Monte Carlo Study Of The Top Quark , Matthias Danniel Hosch

Retrospective Theses and Dissertations

We have studied direct top quark production and single top quark production through anomalous flavor changing chromomagnetic moments. We find that it is possible to detect anomalous flavor changing chromomagnetic moments of the top quark using direct top quark production if the charm quark coupling strength is larger than [kappa]c/[lambda]>.062 TeV-1 at Run 2 of the Tevatron, or larger than [kappa]c/[lambda]>.0084 TeV-1 at the LHC, or if the up quark coupling is larger than [kappa]u/[lambda]>.019 TeV-1 at the Tevatron or larger than [kappa]u/[lambda]>.0033 TeV-1 at the LHC. Single ...


A Search For High Mass Photon Pairs In Pp̄ [Right Facing Arrow][Small Greek Letter Gamma][Small Greek Letter Gamma]Jj Events At [Square Root Of S] = 1.8 Tev , Bryan Adrian Lauer Jan 1997

A Search For High Mass Photon Pairs In Pp̄ [Right Facing Arrow][Small Greek Letter Gamma][Small Greek Letter Gamma]Jj Events At [Square Root Of S] = 1.8 Tev , Bryan Adrian Lauer

Retrospective Theses and Dissertations

A search for new physics in the channel p[bar] p→[gamma][gamma] jj has been carried out. In some extended Higgs models, a light neutral scalar Higgs boson is produced with suppressed couplings to fermions and standard model (SM) strength couplings to vector bosons (bosonic Higgs), thus enhancing the H→[gamma][gamma] channel. We required one photon in the event with EspT[gamma]>30 GeV, |[eta][gamma] |15 GeV, |[eta][gamma] |30 GeV, |[eta]jet |15 GeV, |[eta]jet |<2.25. The final M[gamma][gamma] distribution is consistent with background and no resonance is observed. A 90(95)% confidence level (C.L.) upper limit cross section vs M[gamma][gamma] is calculated, which ranges from 0.60(0.73) pb for M[gamma][gamma] = 65GeV/c2 to 0.24(0.32) pb for M[gamma][gamma]=150GeV/c2. With standard model coupling strengths between the bosonic Higgs and vector bosons, and coupling strengths of zero between the bosonic Higgs and fermions a 90(95)% C.L. bosonic Higgs lower mass limit is set at 90(85) GeV/c2.


Excited Beauty In Delphi , Tony Starr Hill Jan 1995

Excited Beauty In Delphi , Tony Starr Hill

Retrospective Theses and Dissertations

The decay B* → B[gamma] has been observed in the DELPHI detector at LEP, where the B* meson is produced at the Z[superscript]0 resonance. The combination of inclusively reconstructed B mesons with well-measured converted photons yields a measurement of the mean hyperfine splitting in the B meson sector of 46.5±0.3(stat) ± 0.5(syst) MeV. The three flavors of B mesons produced at LEP were not separated in this analysis so this measurement represents an average hyperfine splitting in the B meson sector at the Z[superscript]0 pole. The production ratio of B* mesons ...


Search For Top In Pp̄ Collisions At [Square Root Of S] = 1.8 Tev By Constrained Kinematic Fitting , Myungyun Pang Jan 1994

Search For Top In Pp̄ Collisions At [Square Root Of S] = 1.8 Tev By Constrained Kinematic Fitting , Myungyun Pang

Retrospective Theses and Dissertations

A search for the top quark has been pursued in pp collision at √s = 1.8 TeV with the DO detector. This documentation describes a method introduced to extract the mass of the top quark and the cross section limits on tt production. Also a preliminary result from the DO experiment is described.


A Measurement Of The [Tau Lepton] Polarization At The Z Resonance With The Delphi Detector At Lep , Antonio Wong Chan Jan 1993

A Measurement Of The [Tau Lepton] Polarization At The Z Resonance With The Delphi Detector At Lep , Antonio Wong Chan

Retrospective Theses and Dissertations

The polarization of [tau] leptons produced in the reaction e[superscript]+e[superscript]-→[tau][superscript]+[tau][superscript]- near the peak of the Z° resonance has been measured using a sample of 24904 [tau][superscript]+[tau][superscript]- events, with an estimated background of 1.5%. We have selected 4562 [tau]→ e[nu][macron][nu], 2218 [tau]→[pi][nu] and 5133 [tau]→[rho][nu] candidates. The mean value obtained is P[subscript][tau]=-0.176± 0.029. This corresponds to a ratio of the neutral current vector to the axial-vector coupling constants of the [tau] lepton of g[subscript]spV[tau]/g ...


Topics In Electroweak Baryogenesis: The Sphaleron And T-Violation , Seungkoog Lee Jan 1993

Topics In Electroweak Baryogenesis: The Sphaleron And T-Violation , Seungkoog Lee

Retrospective Theses and Dissertations

Assuming that beyond the standard model physics can be parametrized in terms of high dimensional operators, we examine their effects on the energy of the sphaleron and the classical solution of the gauge and Higgs fields. In the absence of fermions, all of the six dimension 6 operators which are SU(2) symmetric have a small effect when calculated perturbatively. However, calculated non-perturbatively, one of the operators alters the boundary conditions of the equations of motion of the Higgs and gauge fields involved, and another operator gives rise to an abrupt change in the sphaleron energy at a small but ...


A Study Of Isolated Photons In Z0 Hadronic Decays Using The Delphi Detector At Lep , Randall R. Holmes Jan 1992

A Study Of Isolated Photons In Z0 Hadronic Decays Using The Delphi Detector At Lep , Randall R. Holmes

Retrospective Theses and Dissertations

We present a study of the production of energetic isolated photons in the reaction e[superscript]+e[superscript]-→ Z[superscript]0→ q[macron]q[gamma] using the DELPHI detector at LEP. Within the context of the Standard Model, our results for final state radiation show no evidence for anomolous photon production due to rare or new processes. We present a comparison of our data with these theoretical expectations and present upper limits at the 95% CL on the cross section times the branching ratio to hadrons and a photon for the rare or new processes: (1) [sigma](e[superscript]+e ...


Distortions Of Parton Distributions Due To Multiquark Effects , Athanasios Petridis Jan 1992

Distortions Of Parton Distributions Due To Multiquark Effects , Athanasios Petridis

Retrospective Theses and Dissertations

It has been observed that the momentum distributions of partons in bound nuclei are distorted relative to those of free protons and neutrons. This phenomenon was first observed in deep inelastic scattering experiments with muon and neutrino beams on nuclear targets and is known as the EMC effect. Similar phenomena have been observed in other high energy interactions such as the Drell-Yan process, the hadroproduction of direct photons, and the resonance production of charmonium and bottomonium states. In this work we investigate the possibility that these effects are predominantly of partonic origin. Standard nuclear quantum mechanics predicts that there is ...


Multiplicity Distributions From P[Bar]-P Collisions At 1.8 Tev Center Of Mass Energy , Chi-Ho Wang Jan 1991

Multiplicity Distributions From P[Bar]-P Collisions At 1.8 Tev Center Of Mass Energy , Chi-Ho Wang

Retrospective Theses and Dissertations

Charged-particle multiplicity distributions from antiproton-proton collisions at 1800 GeV center of mass energy, obtained with the E735 detector multiplicity hodoscope, are presented and discussed. A simple iteration method is used for conversion from number of observed hodoscope hits to true charged-particle multiplicity. The first four moments of the distribution are compared with distributions from lower energies. The distributions are also fit to KNO-G and negative binomial functions.


Qcd Corrections To Properties Of Technipions In Technicolor Theories , David H. Slaven Jan 1990

Qcd Corrections To Properties Of Technipions In Technicolor Theories , David H. Slaven

Retrospective Theses and Dissertations

In this work we calculate QCD corrections to technipion processes in a one family technicolor model. Our approach is to use an effective technipion Lagrangian analogous to the effective Lagrangian of QCD. The effective Lagrangian includes the Wess-Zumino-Witten Lagrangian (adapted to technicolor), and we gauge the QCD subgroup of the chiral symmetry to obtain couplings between the technipions and gluons. Here we examine processes involving the P[superscript]0[superscript]', a colorless, neutral, electroweak singlet, and the lightest technipion in a one family technicolor model. In addition to the Wess-Zumino-Witten Lagrangian, we assume couplings between technipions and ordinary fermions, due ...


Neutral Technicolor Pseudo Goldstone Bosons Production And Qcd Background At The Ssc , Wang-Chuang Kuo Jan 1990

Neutral Technicolor Pseudo Goldstone Bosons Production And Qcd Background At The Ssc , Wang-Chuang Kuo

Retrospective Theses and Dissertations

The production of the neutral technicolor pseudo Goldstone bosons, P[superscript]0[superscript]' and Psp80[superscript]', at large transverse momentum in pp collisions, pp → g(q)P[superscript]0[superscript]' (Psp80[superscript]')X has been investigated in reactions at a high energy collider such as the SSC. The major two-body and three-body decay modes in tree diagrams are investigated in detail. The t[macron] t decay channel would dominate both the decays of P[superscript]0[superscript]' and Psp80[superscript]' if it is allowed. Otherwise, gg and 3g will be the dominant decay modes unless the mass of the P ...


Measurement Of [Alpha Subscript S]From Energy-Energy Correlations In E+E- Annihilation At 29 Gev , Hsiao-Ying Chao Jan 1990

Measurement Of [Alpha Subscript S]From Energy-Energy Correlations In E+E- Annihilation At 29 Gev , Hsiao-Ying Chao

Retrospective Theses and Dissertations

We have studied the energy-energy correlation in e[superscript]+e[superscript]- annihilation into hadrons at √s = 29 GeV using the TPC/2[gamma] Detector Facility at PEP. We found that [alpha][subscript]s = 0.161 ±.004 ±.011 for the average hadronic event sample using GKS matrix elements and LUND symmetric string fragmentation.


Exclusive Neutral Strange Particle Production From Double Pomeron Exchange Produced By Proton-Proton Interactions At [Square Root Of S] = 62 Gev , John Donovan Skeens Jan 1989

Exclusive Neutral Strange Particle Production From Double Pomeron Exchange Produced By Proton-Proton Interactions At [Square Root Of S] = 62 Gev , John Donovan Skeens

Retrospective Theses and Dissertations

Data are presented for the first time on exclusive Pomeron-Pomeron interactions which produce a neutral strange and neutral antistrange particle pair in a central system X. In this paper, the system, X, is identified as one of the following neutral combinations; K[subscript]sps0K[subscript]sps0, K[subscript]sps0K[superscript]±[pi][superscript][minus or plus], [lambda][superscript]0[macron][lambda][superscript]0, [lambda][superscript]0[macron][lambda][superscript]0*. These data were obtained in proton-proton collisions at √s = 62 GeV at the CERN ISR. The triggering systems used to obtain these data are described, followed by a description of the ...


Superstring-Inspired E6 Phenomenology , Joanne Lea Hewett Jan 1988

Superstring-Inspired E6 Phenomenology , Joanne Lea Hewett

Retrospective Theses and Dissertations

In this study, we examine the low energy phenomenological implications of superstring-inspired E6 models. The motivation for such models is reviewed. New particles, including new gauge bosons, exotic fermions, Higgs bosons, and their superpartners are expected to exist in models of this type. Techniques for producing these new particles directly at existing and planned colliders as well as searching for their indirect effects are examined. Other phenomenological implications of such models are also discussed.


Experimental Study Of Cham Quark Fragmentation , Sung Keun Park Jan 1988

Experimental Study Of Cham Quark Fragmentation , Sung Keun Park

Retrospective Theses and Dissertations

Charm quark fragmentation is studied in e[superscript]+ e[superscript]- annihilation at a center of mass energy of 29 GeV using the time-projection-chamber (TPC) detector at the SLAC storage ring PEP. The polarization of the D[superscript]* +, the energy dependency of the polarization, and the spin density matrix of D[superscript]* + are measured. In 147pb[superscript]-1 of data we see no evidence for polarization, alignment, or final state interaction in this fragmentation process;As a part of elementary particle detector improvement efforts a Radial Drift Chamber (RDC) has been built and studied. The RDC features the use of induced ...


Towards An Understanding Of The Generation Problem , Jerry Allen Robinson Jan 1987

Towards An Understanding Of The Generation Problem , Jerry Allen Robinson

Retrospective Theses and Dissertations

In this study, we examine Hermitian quark mass matrices for three generations and the Kobayashi-Maskawa mixing matrices which they produce. Our investigation is limited to mass matrices which depend on only three parameters. We find that the Fritzsch mass matrix is the unique matrix consisting of five nonzero elements. Then proceeding to classify physically distinct mass matrices having six or seven nonzero elements, we find that several produce mixing matrices that are in good agreement with experimental constraints. Next, we impose constraints obtained from the CP violation parameter [epsilon], B[superscript]0-B[superscript]0 mixing, and the recent observation of ...


Search For Gluonic Bound States In High Energy Proton-Proton Collisions , Larry Donald Isenhower Jan 1986

Search For Gluonic Bound States In High Energy Proton-Proton Collisions , Larry Donald Isenhower

Retrospective Theses and Dissertations

The Double Pomeron Exchange process is studied as a poten- tial source for the production of gluonic bound states utilizing the Intersecting Storage Rings at the European Organization for Nu- clear Research in Geneva, Switzerland. Three different triggers are studied, which differ in the requirements placed on the slow central system produced by the Pomeron-Pomeron interaction;Exclusive four and six prong events are studied. A spin-parity analysis is performed on the (pi)('+)(pi)('-) system in the exclusive channel pp (--->) pp(pi)('+)(pi)('-) for two of the triggers. The large enhancement pre- viously seen in DPE reactions in the region of ...


Higgs-Boson Contributions To Gauge-Bosom Mass Shifts In Extended Electroweak Models , Stephen Richard Moore Jan 1985

Higgs-Boson Contributions To Gauge-Bosom Mass Shifts In Extended Electroweak Models , Stephen Richard Moore

Retrospective Theses and Dissertations

In the minimal standard model, the difference between the tree-level and one-loop-corrected predictions for the gauge-boson masses, known as the mass shifts, are of the order of 4%. The domi- nant contribution is from light-fermion loops. The Higgs-dependent terms are small, even if the Higgs boson is heavy;We have analyzed the mass shifts for models with a more compli- cated Higgs sector. We use the on-shell renormalization scheme, in which the parameters of the theory are the physical masses and couplings. We have considered the 2-doublet, n-doublet, triplet and doublet-triplet models. We have found that the Z-boson mass pre- ...


A Theoretical Study Of Parton Fragmentation And Evolution Into Hadrons , Alexander H. Ng Jan 1984

A Theoretical Study Of Parton Fragmentation And Evolution Into Hadrons , Alexander H. Ng

Retrospective Theses and Dissertations

Jet production via the QCD Compton effect (gamma)q (--->) gq are inves- tigated by using Monte Carlo methods to simulate complete three jet events for photo-nucleon interactions. This process provides unique possibilities for jet studies because the incoming photon transfers its entire energy to the final state gluon and quark jets. We present a number of predictions for photons in the range of energies presently available up to Tevatron energies and find that the QCD Compton effect will dominate over vector meson dominance at large gluon transverse momenta;Also, we present a detailed analysis of single-particle and two-particle inclusive distributions ...


A Study Of Charm Production In Proton-Proton Interactions At √S = 62 Gev With A Forward K¯ Trigger , Mark Steven Gorbics Jan 1984

A Study Of Charm Production In Proton-Proton Interactions At √S = 62 Gev With A Forward K¯ Trigger , Mark Steven Gorbics

Retrospective Theses and Dissertations

The production of charm mesons D('*) and D and their subsequent decays D('*+) (--->) D('0)(pi)('+) and D('0) (--->) K('-)(pi)('+) have been observed in proton-proton interactions at the CERN Intersecting Storage Rings. Using published data for inclusive K('-) and p production cross sections as normalization, the D('*+) production cross section is estimated. For a model with the D('*+) produced with a Feynman-x (x(,F)) distribution of the form (1-x(,F))('2) and a transverse momentum distribution of the form P(,t)*exp(-P(,t)('2)), the D('*('+)) production cross section is estimated to be 23.5 (+OR-) 8.4 ...


Study Of [Pion Pion Right-Facing Arrow] Kk[Macron] And [Pion, Pion, Right-Facing Arrow] Kk[Macron Asterisk] Scattering At 10 Gev/C , Dwight Lee Denney Jan 1982

Study Of [Pion Pion Right-Facing Arrow] Kk[Macron] And [Pion, Pion, Right-Facing Arrow] Kk[Macron Asterisk] Scattering At 10 Gev/C , Dwight Lee Denney

Retrospective Theses and Dissertations

A study of the virtual reactions (pi)('+)(pi)('-) (--->) K('+)K('-) and (pi)('+)(pi)('0) (--->)K('+)K('-)(pi)('+) has been performed using the Large Aperture SolenoidSpectrometer (LASS) at the Stanford Linear Accelerator Center. Amoment analysis of the K('+)K('-) and K('+)K('-)(pi)('+) systems is presented,yielding information on the leading natural spin-parity resonancestates. The well-established states f(1270), f'(1515), and g(1700)are observed, and evidence is presented for a new state with J('p) =;7('-) in the K('+)K('-)(pi)('+) system at a mass of 2720 MeV.;*USDOE Report IS-T-1010. This work was performed under Contract No. W-7405-Eng-82 ...


[Phi] Production And The Ozi Rule In [Greek Letter Pi Superscript +]D Interactions At 10 Gev/C , Joel Stephen Hendrickson Jan 1981

[Phi] Production And The Ozi Rule In [Greek Letter Pi Superscript +]D Interactions At 10 Gev/C , Joel Stephen Hendrickson

Retrospective Theses and Dissertations

A study of the Okubo-Zweig-Iizuka (OZI) rule in (pi)('+)d interactions at 10 GeV/c has been performed using the Large Aperture Solenoid Spectrometer (LASS) at the Stanford Linear Accelerator Center. Measurements of the cross sections (sigma)((pi)('+)n (--->) (phi)p) = 179 (+OR-) 72 nb and (sigma)((pi)('+)p (--->) (phi)(DELTA)('++)) = 172 (+OR-) 75 nb for the OZI forbidden reactions (pi)('+)n (--->) (phi)p and (pi)('+)p (--->) (phi)(DELTA)('++) are consistent with the hypothesis of the phi being produced solely by its nonstrange quark component as determined from the octet-singlet mixing angle resulting from application of the Gell-Mann-Okubo mass formula ...


Phenomenology Based Upon The Generalized Veneziano Model , David Edwin Johnson Jan 1972

Phenomenology Based Upon The Generalized Veneziano Model , David Edwin Johnson

Retrospective Theses and Dissertations

No abstract provided.


A Point And Local Position Operator , Bernice Black Durand Jan 1971

A Point And Local Position Operator , Bernice Black Durand

Retrospective Theses and Dissertations

No abstract provided.


Hyperon-Antihyperon Production In Pp Interactions At 24 And 29 Gev/C , Terry Leroy Schalk Jan 1969

Hyperon-Antihyperon Production In Pp Interactions At 24 And 29 Gev/C , Terry Leroy Schalk

Retrospective Theses and Dissertations

No abstract provided.