Elementary Particles and Fields and String Theory Commons^™

Gauge Transformations Of The Biconformal Connection, James Thomas Wheeler

All Physics Faculty Publications

We study the changes of the biconformal gauge fields under the local rotational and dilatational gauge transformations.

Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre

Research Vignettes

In this worksheet we describe and illustrate a relatively simple set of new Rainich-type conditions on an n-dimensional spacetime which are necessary and sufficient for it to define a perfect fluid solution of the Einstein field equations. Procedures are provided which implement these Rainich-type conditions and which reconstruct the perfect fluid from the metric. These results provide an example of the idea of geometrization of matter fields in general relativity, which is a purely geometrical characterization of matter fields via the Einstein field equations.

Scattering Amplitudes In Flat Space And Anti-De Sitter Space, Savan Kharel

Doctoral Dissertations

We calculate gauge theory one-loop amplitudes with the aid of the complex shift used in the Britto- Cachazo-Feng-Witten (BCFW) recursion relations of tree amplitudes. We apply the shift to the integrand and show that the contribution from the limit of infinite shift vanishes after integrating over the loop momentum, with a judicious choice of basis for polarization vectors. This enables us to write the one-loop amplitude in terms of on-shell tree and lower-point one-loop amplitudes. Some of the tree amplitudes are forward amplitudes. We show that their potential singularities do not contribute and the BCFW recursion relations can be applied …

Supergravity Backgrounds For Deformations Of Adsn×Sn Supercoset String Models, Oleg Lunin, Radu Roiban, Arkady Tseytlin

Physics Faculty Scholarship

We consider type IIB supergravity backgrounds corresponding to the deformed AdS_n x S^n supercoset string models of the type constructed in arXiv:1309.5850 which depend on one deformation parameter k. In AdS_2 x S^2 case we find that the deformed metric can be extended to a full supergravity solution with non-trivial dilaton, RR scalar and RR 5-form strength. The solution depends on a free parameter (called a) that should be chosen as a particular function of k to correspond to the deformed supercoset model. In AdS_3 x S^3 case the full solution supported by the dilaton, RR scalar and RR 3-form …

Gauge Theories Of General Relativity, James Thomas Wheeler

James Thomas Wheeler

General relativity can be seen as a gauge theory of the Lorentz, Poincaré, Weyl, de Sitter, or conformal groups. In most of these, there is little or no difference from the standard formulation in Riemannian geometry, but the higher symmetries — de Sitter and conformal — introduce new features and explain old ones. The potential presence of a cosmological constant, the spacetime metric, cosmological dust, symplectic structure, Kähler structure and even the existence of a timelike direction can all be seen to arise from the underlying group structure.

Nonlinear Dichroism In Back-To-Back Double Ionization Of He By An Intense Elliptically Polarized Few-Cycle Extreme Ultraviolet Pulse, Jean Marcel Ngoko Djiokap, N. L. Manakov, A. V. Meremianin, S. X. Hu, L. B. Madsen, Anthony F. Starace

Anthony F. Starace Publications

Control of double ionization of He by means of the polarization and carrier-envelope phase (CEP) of an intense, few-cycle extreme ultraviolet (XUV) pulse is demonstrated numerically by solving the six-dimensional two-electron, time-dependent Schrödinger equation for He interacting with an elliptically polarized XUV pulse. Guided by perturbation theory (PT), we predict the existence of a nonlinear dichroic effect (∝ I^3/2) that is sensitive to the CEP, ellipticity, peak intensity I, and temporal duration of the pulse. This dichroic effect (i.e., the difference of the two-electron angular distributions for opposite helicities of the ionizing XUV pulse) originates from interference of …

Physics: Rethinking The Foundations, Kevin H. Knuth

Physics Faculty Scholarship

Physics is traditionally conceived of as a set of laws that universally governs the behavior of physical systems. These laws, however they are decreed, are believed to govern the behavior of not only everything in the universe, but the form of the universe itself. However, this traditional concept of physics as a universal governance is at odds with our modern theories of quantum mechanics and relativity, which place the observer and information in a central role. In this talk, I aim to rethink the foundations and attempt to build physics from the bottom up based on a very simple foundational …

Determination Of The Free Neutron Lifetime, J. David Bowman, Leah J. Broussard, Stephen M. Clayton, M. S. Dewey, Nadia Fomin, Keith B. Grammer, G. L. Greene, Paul R. Huffman, Anthony T. Holley, Geoffrey L. Jones, Chenyu Liu, Mark Makela, Michael P. Mendenhall, Charles L. Morris, Jonathan Mulholland, K. M. Nollett, Robert W. Pattie, Seppo Penttila, M. Ramsey-Musolf, Daniel J. Salvat, Andy Saunders, Susan J. Seestrom, William M. Snow, A. Steyerl, F. E. Wietfeldt, Albert R. Young, Andrew T. Yue

Robert W. Pattie Jr.

Effects Of Energetic Irradiation On Materials And Devices Based On Graphene And Topological Insulators, Isaac Childres

Open Access Dissertations

This report focuses on the optical and electronic properties of graphene and topological insulators and how these Dirac fermion systems interact with energetic irradiation. We first present data exploring the effects of electron-beam and oxygen plasma induced disorder on the electronic properties and Raman spectra of graphene. These initial investigations were important for relating Raman peak intensities and weak localization features to each other and to an average disorder length in graphene, L_D. ^ We then integrate gate-effect measurements into the Raman spectroscopy study to fully explore the relationships between carrier density, disorder and Raman spectrum signatures. We …

Beam-Induced Radiation Heating On The Superconducting Undulator At The Advanced Photon Source, Laura Elizabeth Boon

Open Access Dissertations

In January 2013 the Advanced Photon Source (APS), a 7 GeV synchrotron X-ray source, commissioned a Superconducting Undulator (SCU). The superconducting magnet is thermally isolated from the beam vacuum chamber, which absorbs the beam-induced heating. Previous beam induced heat load studies at other laboratories had not included a robust calculation of radiation heating from the upstream dipole magnet. The mitigation of the radiation heating mechanism, and production of photoelectrons to seed an electron cloud was studied for this thesis. ^ An analytical model was developed to predict the radiation heat load on the SCU chamber. This model was benchmarked with …

Studies Of Angular Correlations Of Jets With The Atlas Detector, Rajivalochan Subramaniam

Doctoral Dissertations

The strong force is one of the four fundamental forces and its strength is given by the coupling constant αs. The theory that describes the strong interaction is Quantum Chromodynamics (QCD) and it explains the interactions between quarks and gluons. The strong coupling constant is the only free parameter in the QCD Lagrangian if the quark masses are fixed. Determinations of αs provide direct tests of perturbative QCD calculations. The collimated sprays of particles originating from the quark and gluon interactions are called jets. The ratio of jet cross sections are sensitive to α s and are …

Direct Measurement Of The Pp Solar Neutrino Interaction Rate In Borexino, Keith Otis

Doctoral Dissertations

This dissertation presents the first direct detection of pp solar neutrinos within Borexino, the underground liquid-scintilator detector located at the Gran Sasso National Labratory(LNGS) in Italy, designed to measure the interaction of neutrinos through neutrino-electron elastic scattering. The rate of scattering in Borexino from the pp solar neutrino spectrum is measured to be 155 +/- 16(stat) +/- 13(sys) counts per day per 100 tonnes. With this measurement we are able to rule out the no oscillation hypothesis at the 2-sigma C.L. and the results agree with Standard Solar Model predictions within 1.1-sigma. These neutrinos are from the keystone proton-proton fusion …

Perturbative Unitarity Constraints On A Supersymmetric Higgs Portal, Kassahun Betre, Sonia Hedri, Devin Walker

Faculty Publications

We place perturbative unitarity constraints on both the dimensionful and dimensionless couplings in the Next-to-Minimal Supersymmetric Standard Model Higgs Sector. These constraints, plus the requirement that the singlino and/or Higgsino constitutes at least part of the observed dark matter relic abundance, generate upper bounds on the Higgs and neutralino/chargino mass spectrum. We obtain an upper bound of 12 TeV for the charginos and neutralinos and 20 TeV for the heavy Higgses outside defined fine-tuned regions. By using the NMSSM as a template, we describe a method which replaces naturalness arguments with more rigorous perturbative unitarity arguments to get a better …

Search For New Physical Phenomena Via Displaced Muon Signatures With The Cms Detector At The Lhc, Melih Solmaz

Open Access Theses

The first search at the LHC for long-lived neutral particles decaying to pairs of muons by using only the muon chambers is presented. Events were collected by the CMS detector during pp collisions at √s = 8 TeV and selected from data samples corresponding to 20.5 fb^-1 of integrated luminosity. No background events are expected after the full analysis selection. Expected upper limits are derived for a model which predicts a heavy scalar decaying to two long-lived particles, each of which can decay to muon pairs. Combined expected upper limits with an analysis utilizing the CMS silicon tracker …

Semi-Inclusive Charged-Current Neutrino-Nucleus Reactions, O. Moreno, T. W. Donnelly, J. W. Van Orden, W. P. Ford

Physics Faculty Publications

The general, universal formalism for semi-inclusive charged-current (anti) neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized, and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case …

Analytic Evolution Of Singular Distribution Amplitudes In Qcd, Asli Tandogan

Physics Theses & Dissertations

Distribution amplitudes (DAs) are the basic functions that contain information about the quark momentum. DAs are necessary to describe hard exclusive processes in quantum chromodynamics. We describe a method of analytic evolution of DAs that have singularities such as nonzero values at the end points of the support region, jumps at some points inside the support region and cusps. We illustrate the method by applying it to the evolution of a flat (constant) DA, antisymmetric flat DA, and then use the method for evolution of the two-photon generalized distribution amplitude. Our approach to DA evolution has advantages over the standard …

Investigation And Optimization Of A New Compact Superconducting Cavity For Deflecting And Crabbing Applications, Subashini Uddika De Silva

Physics Theses & Dissertations

Deflecting and crabbing structures have many applications in current accelerator systems. The primary use of a deflecting cavity is to separate a single beam into multiple beams. A crabbing cavity enables the head-on collision at the interaction point in particle colliders in order to increase the luminosity. The early uses of the deflecting structures have been in the early 1960s: these structures were disk loaded structures operating at room temperature. The crabbing structure which was installed at the NEK electron-positron collider was the first and only operational superconducting cavity of that kind. The most common design of superconducting deflecting and …

Initial Conditions In High-Energy Collisions, Elena Petreska

Dissertations, Theses, and Capstone Projects

This thesis is focused on the initial stages of high-energy collisions in the saturation regime. We start by extending the McLerran-Venugopalan distribution of color sources in the initial wave-function of nuclei in heavy-ion collisions. We derive a fourth-order operator in the action and discuss its relevance for the description of color charge distributions in protons in high-energy experiments. We calculate the dipole scattering amplitude in proton-proton collisions with the quartic action and find an agreement with experimental data. We also obtain a modification to the fluctuation parameter of the negative binomial distribution of particle multiplicities in proton-proton experiments. The result …

Yang-Mills Theories As Deformations Of Massive Integrable Models, Axel Cortes Cubero

Dissertations, Theses, and Capstone Projects

Yang Mills theory in 2+1 dimensions can be expressed as an array of coupled (1+1)-dimensional principal chiral sigma models. The SU(N) principal chiral sigma model in 1+1 dimensions is integrable, asymptotically free and has massive excitations. We calculate all the form factors and two- point correlation functions of the Noether current and energy-momentum tensor, in

't Hooft's large-N limit (some form factors can be found even at finite N). We use these new form factors to calculate physical quantities in (2+1)-dimensional Yang-Mills theory, generalizing previous SU(2) by P. Orland to SU(N). The anisotropic gauge theory is related to standard isotropic …

Perihelion Precession In General Relativity, Charles G. Torre

Charles G. Torre

This is a Maple worksheet providing a relatively quick and informal sketch of a demonstration that general relativistic corrections to the bound Kepler orbits introduce a perihelion precession. Any decent textbook will derive this result. My analysis aligns with that found in the old text "Introduction to General Relativity", by Adler, Bazin and Schiffer. The plan of the analysis is as follows. * Model the planetary orbits as geodesics in the (exterior) Schwarzschild spacetime. * Compute the geodesic equations. * Simplify them using symmetries and first integrals. * Isolate the differential equation expressing the radial coordinate as a function of …

Studies Of Charge Collection In Diamond-Based Particle Detectors At The Lhc, Jared Smith

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

See file

Dark Matter As An Integral Part Of An Alternative Gravity Model, Hontas Farmer

Hontas F Farmer

The purpose of this paper is to reconcile observations of dark matter effects on the galactic and cosmological scales with the null results of astroparticle physics observations such as CDMS and ANTARES. This paper will also provide a candidate unified and simpler mathematical formulation for the Lambda CDM model. Unification is achieved by a combination of the f(R) approach, with the standard LCDM approach and inflationary models. It is postulated that dark matter-energy fields depend on the Ricci curvature R. Standard methods of classical and quantum field theory on curved space time are applied. When this model is treated as …

A Method For Measuring Coherent Elastic Neutrino-Nucleus Scattering At A Far Off-Axis High-Energy Neutrino Beam Target

Robert W. Pattie Jr.

Direct Measurements Of Two Photon Exchange On Lepton-Proton Elastic Scattering Using Simultaneous Electron-Positron Beams In Clas, Dasuni Kalhari Adikaram

Physics Theses & Dissertations

The electric (GE) and magnetic ( GM) form factors of the proton are fundamental observables which characterize its charge and magnetization distributions. There are two methods to measure the proton form factors: the Rosenbluth separation method and the polarization transfer technique. However, the ratio of the electric and magnetic form factors measured by those methods significantly disagree at momentum transfer Q² > 1 GeV². The most likely explanation of this discrepancy is the inclusion of two-photon exchange (TPE) amplitude contributions to the elastic electron-proton cross section which significantly changes the extraction of GE from the …

Conformal Gravity Holography In Four Dimensions, Robert Mcnees

Robert A McNees IV

We formulate four-dimensional conformal gravity with (anti–)de Sitter boundary conditions that are weaker than Starobinsky boundary conditions, allowing for an asymptotically subleading Rindler term concurrent with a recent model for gravity at large distances. We prove the consistency of the variational principle and derive the holographic response functions. One of them is the conformal gravity version of the Brown–York stress tensor, the other is a “partially massless response”. The on shell action and response functions are finite and do not require holographic renormalization. Finally, we discuss phenomenologically interesting examples, including the most general spherically symmetric solutions and rotating black hole …

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

Charles G. Torre

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 …

Resonant Electron-Atom Bremsstrahlung In An Intense Laser Field, A. N. Zheltukhin, A. V. Flegel, M. V. Frolov, N. L. Manakov, Anthony F. Starace

Anthony F. Starace Publications

We analyze a resonant mechanism for spontaneous laser-assisted electron bremsstrahlung (BrS) involving the resonant transition (via either laser-assisted electron-ion recombination or electron-atom attachment) into a laser-dressed intermediate quasibound state (corresponding, respectively, to either a field-free neutral atom or a negative-ion bound state) accompanied by ionization or detachment of this state by the laser field. This mechanism leads to resonant enhancement (by orders of magnitude) of the BrS spectral density for emitted photon energies corresponding to those for laser-assisted recombination or attachment. We present an accurate parametrization of the resonant BrS amplitude in terms of the amplitudes for nonresonant BrS, for …

Gauge/ Gravity Correspondence, Bulk Locality And Quantum Black Holes, Debajyoti Sarkar

Dissertations, Theses, and Capstone Projects

The aim of this dissertation is threefold. We begin by the study of two parallel ideal cosmic strings in the presence of non-minimal scalar fields and spin- 1 gauge fields. We show that the contributions of the non-minimal term on the interaction energy between the strings are similar to that of the gauge field for a particular value of non-minimal coupling parameter. In this context we clarify some of the issues that arise when comparing the renormalization of black hole entropy and entanglement entropy using the replica trick.

In the second part of the dissertation we study the process of …

Algebraic Formulation Of Hadronic Supersymmetry Based On Octonions: New Mass Formulas And Further Applications, Sultan Catto, Yasemin Gürcan, Amish Khalfan, Levent Kurt

Publications and Research

A special treatment based on the highest division algebra, that of octonions and their split algebraic formulation is developed for the description of diquark states made up of two quark pairs. We describe symmetry properties of mesons and baryons through such formulation and derive mass formulae relating π, ρ, N and Δ trajectories showing an incredible agreement with experiments. We also comment on formation of diquark-antidiquark as well as pentaquark states and point the way toward applications into multiquark formulations expected to be seen at upcoming CERN experiments. A discussion on relationship of our work to flux bag models, string …

A Numerical Assessment Of Cosmic-Ray Energy Diffusion Through Turbulent Media, M. Fatuzzo, F. Melia

Faculty Scholarship

No abstract provided.