Elementary Particles and Fields and String Theory Commons^™

Limits On Violations Of Lorentz Symmetry From Gravity Probe B, Quentin G. Bailey, Ryan D. Everett, James M. Overduin

Physics & Astronomy - Prescott

Generic violations of Lorentz symmetry can be described by an effective field theory framework that contains both general relativity and the Standard Model of particle physics called the Standard-Model extension (SME). We obtain new constraints on the gravitational sector of the SME using recently published final results from Gravity Probe B. These include for the first time an upper limit at the 10_3 level on the time-time component of the new tensor field responsible for inducing local Lorentz violation in the theory, and an independent limit at the 10_7 level on a combination of components of this tensor field.

Carrier-Envelope-Phase-Induced Asymmetries In Double Ionization Of Helium By An Intense Few-Cycle Xuv Pulse, Jean Marcel Ngoko Djiokap, N. L. Manakov, A. V. Meremianin, Anthony F. Starace

Anthony F. Starace Publications

The carrier-envelope-phase (CEP) dependence of electron angular distributions in double ionization of He by an arbitrarily polarized, few-cycle, intense XUV pulse is formulated using perturbation theory (PT) in the pulse amplitude. Owing to the broad pulse bandwidth, interference of first- and second-order PT amplitudes produces asymmetric angular distributions sensitive to the CEP. The PT parametrization is shown to be valid by comparing with results of solutions of the full-dimensional, two-electron time-dependent Schrödinger equation for the case of linear polarization.

Harmonic Generation Spectroscopy With A Two-Colour Laser Field Having Orthogonal Linear Polarizations, T. S. Sarantseva, M. V. Frolov, N. L. Manakov, M. Yu. Ivanov, Anthony F. Starace

Anthony F. Starace Publications

The interpretation of many high-order harmonic generation (HHG) experiments is based on the assumption that the HHG yield of an atom can be factorized into (i) a laser-dependent ‘electron wave packet’ with rather simple properties, including a nearly universal shape, and (ii) an atomic photorecombination cross section. We show that this factorization is restricted to linearly polarized laser fields and fails in two-colour laser fields with orthogonal polarizations. At the same time, we show how two-colour HHG spectroscopy using orthogonally polarized intense fundamental and relatively weak second harmonic fields makes a complete experiment possible that enables the retrieval of the …

Rainich-Type Conditions For Null Electrovacuum Spacetimes Ii, Charles G. Torre

Research Vignettes

In this second of two worksheets I continue describing local Rainich-type conditions which are necessary and sufficient for the metric to define a null electrovacuum. In other words, these conditions, which I will call the null electrovacuum conditions, guarantee the existence of a null electromagnetic field such that the metric and electromagnetic field satisfy the Einstein-Maxwell equations. When it exists, the electromagnetic field is easily constructed from the metric. In this worksheet I consider the null electrovacuum conditions which apply when a certain null geodesic congruence determined by the metric is twisting. I shall illustrate the these conditions using a …

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 …

Comment On "Unified Formalism Of Adreev Reflection At A Ferromagnet/Superconductor Interface", M. Eschrig, A. A. Golubov, I. I. Mazin, B. Nadgorny, Y. Tanaka, O. T. Valls, Igor Žutić

Physics and Astronomy Faculty Research Publications

A Comment on the Letter by T. Y. Chen et al., Phys. Rev. Lett. 109 146602 (2012) The authors of the Letter offer a Reply.

Freeze-Out Dynamics Via Charged Kaon Femtoscopy In √ Snn = 200 Gev Central Au + Au Collisions, L. Adamczyk, E. Elnimr, S. Lapointe, C. Pruneau, J. Putschke, M. Sharma, L. H. Tarini, S. A. Voloshin, Star Collaboration

Physics and Astronomy Faculty Research Publications

We present measurements of three-dimensional correlation functions of like-sign, low-transverse-momentum kaon pairs from √s_NN=200 GeV Au+Au collisions. A Cartesian surface-spherical harmonic decomposition technique was used to extract the kaon source function. The latter was found to have a three-dimensional Gaussian shape and can be adequately reproduced by Therminator event-generator simulations with resonance contributions taken into account. Compared to the pion one, the kaon source function is generally narrower and does not have the long tail along the pair transverse momentum direction. The kaon Gaussian radii display a monotonic decrease with increasing transverse mass m_T over …

Freeze-Out Dynamics Via Charged Kaon Femtoscopy In √ S N N = 200 Gev Central Au + Au Collisions, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

We present measurements of three-dimensional correlation functions of like-sign, low-transverse-momentum kaon pairs from √sNN=200 GeV Au+Au collisions. A Cartesian surface-spherical harmonic decomposition technique was used to extract the kaon source function. The latter was found to have a three-dimensional Gaussian shape and can be adequately reproduced by Therminator event-generator simulations with resonance contributions taken into account. Compared to the pion one, the kaon source function is generally narrower and does not have the long tail along the pair transverse momentum direction. The kaon Gaussian radii display a monotonic decrease with increasing transverse mass mT over the interval of 0.55≤m_{T …}

Ttbar Production Cross Section Measurement In The Muon Plus Jets Channel Using Soft Electron Tagging In Pp Collisions At Sqrt(S) = 8 Tev, Jason Keller

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

A measurement is made of the top quark pair production cross section through the decay channel ttbar -> mu nu + jets, carried out using the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC), located at CERN in Geneva, Switzerland. The top quark pair events were produced in proton-proton collisions at a center-of-mass energy of 8 TeV. To facilitate the detection of ttbar events, jets produced from bottom quarks, which are decay products of the top quarks, are identified using electrons with low transverse momentum with respect to the beam axis (soft electrons). The dominant background, W …

Project X: Physics Opportunities, Andreas S. Kronfeld, Robert S. Tschirhart, Usama Al-Binni, Wolfgang Altmannshofer, Charles Ankenbrandt, Kaladi Babu, Sunanda Banerjee, Matthew Bass, Brian Batell, David V. Baxter, Zurab Berezhiani, Marc Bergevin, Robert Bernstein, Sudeb Bhattacharya, Mary Bishai, Thomas Blum, S. Alex Bogacz, Stephen J. Brice, Joachim Brod, Alan Bross, Michael Buchoff, Thomas W. Burgess, Marcela Carena, Luis A. Castellanos, Subhasis Chattopadhyay, Mu-Chun Chen, Daniel Cherdack, Norman H. Christ, Tim Chupp, Vincenzo Cirigliano, Pilar Coloma, Christopher E. Coppola, Ramanath Cowsik, J. Allen Crabtree, André De Gouvêa, Jean-Pierre Delahaye, Dmitri Denisov, Patrick Deniverville, Ranjan Dharmapalan, Alexander Dolgov, Georgi Dvali, Estia Eichten, Jürgen Engelfried, Phillip D. Ferguson, Tony Gabriel, Avraham Gal, Franz Gallmeier, Kenneth S. Ganezer, Susan Gardner

Robert W. Pattie Jr.

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 …

The Spacetime Geometry Of A Null Electromagnetic Field, Charles G. Torre

Presentations and Publications

We give a set of local geometric conditions on a spacetime metric which are necessary and sufficient for it to be a null electrovacuum, that is, the metric is part of a solution to the Einstein-Maxwell equations with a null electromagnetic field. These conditions are restrictions on a null congruence canonically constructed from the spacetime metric, and can involve up to five derivatives of the metric. The null electrovacuum conditions are counterparts of the Rainich conditions, which geometrically characterize non-null electrovacua. Given a spacetime satisfying the conditions for a null electrovacuum, a straightforward procedure builds the null electromagnetic field from …

Third Harmonic Flow Of Charged Particles In Au + Au Collisions At √ S Nn = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, Av. V. Alakhverdyants, I. Alekseev, S. Bültmann, I. Koraly, Star Collaboration

Physics Faculty Publications

We report measurements of the third harmonic coefficient of the azimuthal anisotropy, v₃, known as triangular flow. The analysis is for charged particles in Au+Au collisions at √sNN=200 GeV, based on data from the STAR experiment at the BNL Relativistic Heavy Ion Collider. Two-particle correlations as a function of their pseudorapidity separation are fit with narrow and wide Gaussians. Measurements of triangular flow are extracted from the wide Gaussian, from two-particle cumulants with a pseudorapidity gap, and also from event plane analysis methods with a large pseudorapidity gap between the particles and the event plane. These results are …

Asymmetries In Production Of He+(N = 2) With An Intense Few-Cycle Attosecond Pulse, Jean Marcel Ngoko Djiokap, S. X. Hu, Wei-Chao Jiang, Liang-You Peng, Anthony F. Starace

Anthony F. Starace Publications

By solving the two-electron time-dependent Schrödinger equation, we study carrier-envelope-phase (CEP) effects on ionization plus excitation of He to He⁺(n = 2) states by a few-cycle attosecond pulse with a carrier frequency of 51 eV. For most CEPs the asymmetries in the photoelectron angular distributions with excitation of He⁺(2s) or He⁺(2p) have opposite signs and are two orders of magnitude larger than for ionization without excitation. These results indicate that attosecond pulse CEP effects may be significantly amplified in correlated two-electron ionization processes.

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 …

Information-Based Physics: An Intelligent Embedded Agent's Guide To The Universe, Kevin H. Knuth

Physics Faculty Scholarship

In this talk, I propose an approach to understanding the foundations of physics by considering the optimal inferences an intelligent agent can make about the universe in which he or she is embedded. Information acts to constrain an agent’s beliefs. However, at a fundamental level, any information is obtained from interactions where something influences something else. Given this, the laws of physics must be constrained by both the nature of such influences and the rules by which we can make inferences based on information about these influences. I will review the recent progress we have made in this direction. This …

Session E-4: What's Up With The Higgs Boson? Teaching Particle Physics In High School, Peter Dong

Professional Learning Day

Best-selling books, popular PBS specials, and multi-billion-dollar machines all attest to the fascination with particle physics - including many teenagers. Physics and physical science classes can capitalize on this interest by talking about high-profile results, such as last summer's Higgs Boson Discovery. This session will answer some basic questions about contemporary particle physics and suggest some ideas for lessons and projects in particle physics.

How To Find Killing Vectors, Charles G. Torre

How to... in 10 minutes or less

We show how to compute the Lie algebra of Killing vector fields of a metric in Maple using the commands KillingVectors and LieAlgebraData. A Maple worksheet and a PDF version can be found below.