Elementary Particles and Fields and String Theory Commons^™

Measurement Of [Special Characters Omitted] (Pp[Special Characters Omitted]Tt) In The[Special Characters Omitted]+ Jets Channel Using 4.7 Fb-1 Of Data From The Atlas Experiment Of The Large Hadron Collider, Anirvan Sircar

Doctoral Dissertations

The top quark is the heaviest of the known elementary particles in the Standard Model. Top quark decay can result into various final states; therefore, careful study of its production rate and other properties is very important for particle physics. With the shutdown of the Tevatron, The Large Hadron Collider (LHC) is the only facility currently capable of studying top quark properties. The data obtained by proton-proton collisions in the LHC is recorded by two general purpose detectors, ATLAS and CMS. The results in the dissertation are from the ATLAS detector. A new measurement is reported of &sgr;(pp [special …

Contributions To The Cuore Collaboration, Samuel Joseph Meijer

Physics

This paper describes work done between 2010 and 2013 to contribute to the CUORE collaboration, a physics collaboration searching for neutrinoless double-beta decay in tellurium. Measurement of this decay would indicate fundamental information about the nature of the neutrino. The implementation of a parylene-coated detector frame is described. Also, a temperature stabilization system for an automated gluing system was constructed. An image recognition algorithm is described for locating spots of glue and evaluating their acceptability.

Field Emission Studies Toward Improving The Performance Of Dc High Voltage Photoelectron Guns, Mahzad Bastaninejad

Mechanical & Aerospace Engineering Theses & Dissertations

Field emission is the main mechanism that prevents DC high voltage photoemission electron guns from operating at the very high bias voltages required to produce low emittance beams. Gas conditioning is shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. The field emission characteristics of 5 stainless steel electrodes varied significantly upon the initial application of voltage but improved to nearly the same level …

Contributions To Background Reduction And Computer Simulations For Cuore & Cuore-0, Ivo J. Plamenac

Physics

CUORE and CUORE-0 aim to observe neutrinoless double beta decay in ¹³⁰Te; observing such this particular decay would substantiate the Majorana model for the neutrino and expand our current understanding of particle physics. This report will provide an overview of the Standard Model, our current framework for particle interactions, as well as the technical details of the CUORE experiment. Over the summers of 2010 and 2011, I contributed to the efforts of the CUORE collaboration by assisting in aspects such as background reduction, and explored detector behavior using computer simulations.

Double Spin Asymmetry In D →(E→E'P)N, Michael Mayer

Physics Theses & Dissertations

Using the CLAS detector at Jefferson Lab, double spin asymmetries (A ∥) for quasi-elastic electron scattering off the deuteron have been measured at several beam energies. The data were collected during the EG1 experiment, which scattered longitudinally polarized electrons with energies from 1.6 to 5.8 GeV off a longitudinally polarized cryogenic ND₃ target. The double spin asymmetries were measured as a function of photon virtuality Q² (0.13-3.17 (GeV/c)2), missing momentum (0.0-0.5 GeV/c), and the angle between the (inferred) "spectator" neutron and the momentum transfer direction (θ_ng). The results from EG1b are compared with a recent model …

Using Heavy Flavors To Study New Physics, Kristopher Jason Healey

Wayne State University Dissertations

In this doctoral dissertation I discuss the possible standard model contributions to select leptonic heavy meson decay modes. Included are calculations of soft photon contributions to a di-lepton decay of B-mesons as well as two-particle hadronic unitary contributions to the rare di-leptonic decay of the neutral D meson. Additionally, constraints are calculated for two super-WIMP dark matter models from rare heavy flavor decays.

Investigation Of Spin-Independent Cp Violation In Neutron And Nuclear Radiative Β Decays, Daheng He

Theses and Dissertations--Physics and Astronomy

CP violation is an important condition to explain the preponderance of baryons in our universe, yet the available CP violation in the Standard Model (SM) via the so-called Cabibbo-Kobayashi-Maskawa mechanism seems to not provide enough CP violation. Thus searching for new sources of CP violation is one of the central tasks of modern physics. In this thesis, we focus on a new possible source of CP violation which generates triple-product correlations in momenta which can appear in neutron and nuclear radiative β decay. We show that at low energies such a CP violating correlation may arise from the exotic coupling …

Massive Gravity Theories, Greg Seyfarth

Honors Theses

We examine Fierz and Pauli's work in 1939 of adding a mass term to the Lagrangian for linearized gravity with the form ?? where h is a small perturbation away from flat spacetime and showing that the only value for ? which gives a ghost-free theory with the correct five degrees of freedom expected for a massive spin- 2 particle such as the graviton is ? [1]. We start by rederiving the Lagrangian formulation for classical electrodynamics and giving examples of a ghost. Then we solve the linearized massless gravity equations to show their two degrees of freedom. We perform …

Measurement Of Polarized Proton-Proton Elastic Scattering At The Relativistic Heavy Ion Collider (Rhic), Ivan Koralt

Physics Theses & Dissertations

Elastic proton-proton (pp) scattering is one of the most fundamental processes in nature and yet, it is one of the most difficult to describe. There are two interactions involved in this process: electromagnetic (Coulomb) and hadronic (strong) interactions. Underlying exchange mechanisms of these two interactions are the virtual photon and the Pomeron exchange, respectively. The difficulty of elastic pp scattering arises from the fact that the nature of the Pomeron and its exchange are not well understood and need a theoretical approach, which is still under development.

At the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab …

Condensed Matter From Gauge/Gravity Duality, Jason Edward Therrien

Doctoral Dissertations

Currently strongly coupled systems present the greatest challenge to theoretical physics. For years conventional methods of approach have failed to describe these systems analytically. In recent years it has been shown that there is a duality between weakly coupled and strongly coupled systems, the Gauge Theory/Gravity Duality. In this dissertation I will discuss how the AdS/CFT is used to describe strongly coupled condensed matter systems as well as present the work done by the author and collaborators.

Measurement Of Theta-13 Neutrino Mixing Angle From The Disappearance Of Electron Antineutrinos At The Double Chooz Experiment, Brandon Reed White

Doctoral Dissertations

The measurement of the remaining neutrino-mixing angle, theta-130, is a critical step toward further understanding of neutrino properties and to guide future neutrino oscillation experiments. Double Chooz has a unique opportunity to perform this measurement building on the original CHOOZ reactor anti-neutrino experiment, the experience that set the previous limits on theta-13. In the first phase of Double Chooz, 101 days of data was analyzed with only the far detector operating of a two-detector plan. In this thesis I will describe the design of the low background neutrino detector and the oscillation analysis performed. From the deficiency between the expected …

Building An Alpha Spectrometer For The Cuore Collaboration, David J. Miller

Physics

This paper will give the reader a brief introduction to the Standard Model, Neutrinoless Double Beta Decay (0νββ), and the CUORE experiment under construction at Gran Sasso National Lab in Assergi, Italy. The remainder of the paper will describe the process of creating a working alpha spectrometry system using silicon detectors and NIM and CAMAC electronics. Extensive details of the troubleshooting and calibration period are presented as a way for the reader to better understand the concepts involved in alpha spectroscopy and to not repeat mistakes made in this development process.

Topics In Field Theory, Alexander Patrushev

Electronic Thesis and Dissertation Repository

This thesis consists of different projects in classical and quantum field theory on a curved background which are connected by a common usage of theoretical ideas as well as cal- culation techniques. The introduction clarifies such connections. In the second chapter we apply the Dirac constraint formalism to the second and first order 1 + 1 dimensional gravitational action coupled to a scalar field. The third chapter is devoted to a calculation of the one loop effective action for a spinor field coupled to a constant background chiral vector field. In the fourth chapter we find a new expression for …

Ads/Cft In String Theory And M-Theory, Daniel R. Gulotta '03

Doctoral Dissertations

The AdS/CFT correspondence is a powerful tool that can help shed light on the relationship between geometry and field theory.

The first part of this thesis will focus on the construction of theories dual to Type IIB string theory on AdS₅ x Y⁵, where Y⁵ is a toric Sasaki-Einstein manifold. This thesis will introduce a consistency condition called "proper ordering" and demonstrate that it is equivalent to several other previously known consistency conditions. It will then give an efficient algorithm that produces a consistent field theory for any toric Sasaki-Einstein Y⁵.

The second part …

Gain Of A Single Gas Electron Multiplier, Mythra Varun Nemallapudi

Graduate Theses and Dissertations

Gas Electron Multiplier (GEM) is a gaseous detector used in particle detection and is

known for its high rate capability. Ever since its invention in 1997, GEM was applied in

many areas and recently has been proposed to be installed in the CMS high η regions for

upgrade at LHC, CERN. A complete understanding of the working and gain behaviour does

not exist. GEM gain is influenced by charging up and this has been variedly interpreted

in literature lacking consensus. I have attempted in this work through simulations and

measurements to achieve a better understanding of single GEM gain and …

Study Of Jet Transverse Momentum And Jet Rapidity Dependence Of Dijet Azimuthal Decorrelations With The Dø Detector, Kiran Chakravarthula

Doctoral Dissertations

In a collision experiment involving highly energetic particles such as hadrons, processes at high momentum transfers can provide information useful for many studies involving Quantum Chromodynamics (QCD). One way of analyzing these interactions is through angular distributions. In hadron-hadron collisions, the angular distribution between the two leading jets with the largest transverse momentum (pT) is affected by the production of additional jets. While soft radiation causes small differences in the azimuthal angular distribution of the two leading jets produced in a collision event, additional hard jets produced in the event have more pronounced influence on the distribution of …

The Study Of Pt Dependence Of Dijet Azimuthal Decorrelations In Proton-Proton Collision At Center Of Mass Energy = 7 Tev, Ramasudhakar Dhullipudi

Doctoral Dissertations

The transverse momentum (pT) dependence of azimuthal decorrelations in dijet events is studied with data collected, at an integrated luminosity of [special characters omitted] dt = (36 ± 4) pb−1, from collisions between protons at a center of mass energy of [special characters omitted] = 7 TeV using the ATLAS detector at the Large Hadron Collider. The results of the analysis of jets in a central rapidity of |y| < 0.8 and pT in the range 60 GeV < pT < 1200 GeV are presented. A new observable RΔ&phis;, defined as the fraction of the total dijet cross section corresponding to a particular range of …

Event Shapes In Proton-Proton Collisions At Center Of Mass Energy = 1.96 Tev, Scott Atkins

Doctoral Dissertations

This dissertation presents the analysis of nine different event shapes measured in high energy pp¯ collisions. An event shape can be defined as an event-based quantity that measures how the final energies are distributed in the final event. This analysis will test strong interactions as described by Quantum Chromodynamics (QCD), through their implementation in different Monte Carlo-based models. Each of the event shapes provides information about the flow of energy in QCD events and about the hadronic final states that occur in pp¯ particle collisions, thus allowing the study of the dynamics of QCD multijet events. Any deviation of an …

The Search For Charged Massive Supersymmetric Particles At The Lhc, Aleksey Pavlov

Physics

Charged Massive Particles (CHAMPs) are predicted in the Supersymmetry (SUSY) extension of the Standard Model though they have never been ob- served. We look for CHAMPs in the ALICE Detector at the Large Hadron Collider at CERN. While the main purpose of ALICE is to study Quark- Gluon Plasma, we take advantage of the tracking and time of flight capabilities of several sub-detectors in ALICE to look for signs of CHAMPs. These elusive particles are characterized by their slow velocity, high transverse momentum and therefore heavy mass. Our research found a small handful of candidates among a large sample size …

Study Of The Structure Of 9C Via Single Neutron Transfer, Scott T. Marley

Dissertations

This thesis describes a study of the nucleus ⁹C, produced in the single-neutron transfer reaction d(¹⁰C, t) ⁹C using a radioactive ¹⁰C beam. The structure of the neutron-deficient nucleus ⁹C is poorly known. Only a few excited states have been observed and no information exists of their single-particle characteristics. The measured ground-state magnetic dipole moment of ⁹C is anomalously small and could imply large contributions from sd-shell orbitals in the ground-state wave function. The positions of the ⁹C excited states and their single-particle properties are vital to furthering the …

Measurement Of Production And Decay Properties Of Bs Mesons Decaying Into J/Psi Phi With The Cms Detector At The Lhc, Giordano Cerizza

Doctoral Dissertations

The production of hadrons containing b-quarks has been measured in proton anti-proton collisions up to center-of-massenergies of 1.96 TeV at the Tevatron. Information at lower energy is provided by electron-positron collision experiments.The underlying theory of hadronic interactions is tuned to those data but cannot reliably predict reaction rates from first principlesfor higher energies. Therefore, it is important to test the extrapolations and optimize model parameters for the new energy regime at the LHC. The b-hadrons from proton-proton collisions are a major source of background in searches for the Higgs boson andother heavy not-yet-discovered particles. Hence, it is important to quantify …

Single And Double Spin Asymmetries For Pion Electro-Production From The Deuteron In The Resonance Region, Sharon L. Careccia

Physics Theses & Dissertations

The single and double spin asymmetries A_t and A_et have been measured in π^- electro-production off the deuteron using a longitudinally polarized electron beam and a polarized ND₃ target. The electron beam was polarized using a strained GaAs cathode and the target was polarized using Dynamic Nuclear Polarization. The data were collected at beam energies of 1.6, 1.7, 2.5 and 4.2 GeV in Hall B at Jefferson Lab in the spring of 2001. The final state particles were detected in the CEBAF Large Acceptance Spectrometer (CLAS). The d(e,e'π-p)p exclusive channel was identified using the missing mass …

Calculation Of Physical Processes At The Lhc, Usama Adnan Al-Binni

Doctoral Dissertations

With the start of the age of the Large Hadron Collider (LHC) two challenges face theoreticians and computational physicists. The first is about understanding theories beyond the Standard Model and producing verifiable predictions that can be tested against what the LHC and subsequent machines would produce. The second is to improve computational methods so that the new experimental precision is matched by a theoretical one. But this improvement is also crucial for the detection of potential deviations from Standard Model predictions and possibly also finding the elusive Higgs. This work tries to address problems in both areas. In the first …

Thermodynamics, Hydrodynamics And Critical Phenomena In Strongly Coupled Gauge Theories, Christopher Pagnutti

Electronic Thesis and Dissertation Repository

The gauge theory / string theory correspondence has led to great progress in the study of strongly-coupled gauge theories. In this work, we start with a detailed treatment of some simple examples of this correspondence in order to establish some of the concepts and techniques are used on a more complicated system. We then consider a (3+1)-dimensional theory of gravity with a translationally invariant horizon, that is assumed to be dual to a (2+1)-dimensional non-conformal gauge theory at finite temperature. We study the thermodynamics of this model and find that there exists an exotic type of second-order phase transition wherein …

Triple Coincidence Beam Spin Asymmetry Measurements In Deeply Virtual Compton Scattering, Mustafa Canan

Physics Theses & Dissertations

The Generalized Parton Distributions (GPDs) provides hitherto the most complete information about the quark structure of hadron. GPDs are accessible through hard-exclusive reactions, among which Deeply Virtual Compton Scattering (DVCS) is the cleanest reaction. A dedicated DVCS experiment on Hydrogen (E00-110) ran in the Hall A at Jefferson Laboratory in Fall 2004. I present here Beam Spin Asymmetry (BSA) results for the ep → epγ reaction studied in the E00-110 experiment with fully exclusive triple coincidence H(e, e'γp ) detection. I present a re-calibration of the electromagnetic calorimeter used to detect the high energy photon. This calibration …

Gauge-Gravity Duality And Its Applications To Cosmology And Fluid Dynamics, Jae-Hyuk Oh

University of Kentucky Doctoral Dissertations

This thesis is devoted to the study of two important applications of gauge-gravity duality: the cosmological singularity problem and conformal fluid dynamics. Gauge-gravity duality is a concrete dual relationship between a gauge theory (such as electromagnetism, the theories of weak and strong interactions), and a theory of strings which contains gravity. The most concrete application of this duality is the AdS/CFT correspondence, where the theory containing gravity lives in the bulk of an asymptotically anti-de-Sitter space-time, while the dual gauge theory is a deformation of a conformal field theory which lives on the boundary of anti-de-Sitter space-time(AdS).

Our first application …

Magnetic-Field Induced Stability In Two-Flavor Color Superconductivity, Churna B. Bhandari

Open Access Theses & Dissertations

It has long been understood that the ground state of a superdense quark system, a Fermi liquid of weakly interacting quarks, is unstable with respect to the formation of diquark condensates. This nonperturbative phenomenon is essentially equivalent to the Cooper instability of conventional BCS superconductivity. As the quark pairs have nonzero color charge, this kind of superconductivity breaks the SU(3) color gauge symmetry, thus it is called color superconductivity. A peculiar feature of spin-zero color superconductivity is the lack of Meissner effect for a combination of the regular electromagnetic field and one of the gluon fields. This combination behaves as …

Electron Transmission Characteristics And The Production Of Narrow Beams Using Glass Optics, Buddhika Senarath Dassanayake

Dissertations

Transmission of electrons through an insulating single cylindrically-shaped glass capillary of microscopic dimension has been investigated. Samples made with Borosilicate glass (PYREX 7740) were subjected to bombardment of 300-1000 eV electrons. Transmitted electrons were analyzed using a parallel-plate spectrometer coupled to a channel electron multiplier.

The transmitted electron intensity was found to decrease with increasing sample tilt angle relative to the direction of the primary beam. Two regions of transmission were found: direct where there is no interaction of the beam with the inner capillary wall, and indirect where the beam does interact with the wall. The rate of transmission …

Photoproduction Of The Φ(1020) Meson In Neutral Decay Mode Γp → Φp → K(S)K(L)P, Heghine Seraydaryan

Physics Theses & Dissertations

The Φ(1020) meson photoproduction cross sections in the neutral decay mode Φ → K_SK_L are measured for the first time. This work presents measurements of differential cross sections, dσ/dt, dσ/d cos θ^Φ_c.m.; Φ decay angular distributions, W(cos θ) and W(Φ), and spin-density matrix elements, ρ⁰, in the Helicity and Gottfried-Jackson frames, in the energy range 1.6 GeV < E_γ < 2.6 GeV. We analyzed the photoproduction data of the g11a experiment collected on an LH2 target using the CLAS detectector at Hall B, TJNAF. The measured cross sections show some differences from the charged decay mode Φ → K⁺ K⁻.

Could Alice Find The Elusive Higgs?, Tyler Williams

Physics

The Higgs boson is the theoretical mechanism for creating the mass of particles. Although it has never been seen, the CERN Large Hadron Collider (LHC) is the most likely place for it to be created in the laboratory. The ALICE (A Large Ion Collider Experiment) detector is focused on the study of heavy ion collisions at the LHC and was not designed to find the Higgs boson; however, there is a chance it could be detected there. Although the luminosity (collision rate) for PbPb collisions is much lower than that for pp collisions, PbPb collisions have a higher probability to …