Physics Commons^™

Observability Of The Anapole Moment And Neutrino Charge Radius, Mj Musolf, Br Holstein

Barry R Holstein

The properties of the neutrino charge radius (NCR) and anapole moments (AM's) of elementary fermions, nucleons, and nuclei are discussed. The dependence of these off-shell electromagnetic couplings on the weak gauge parameter is explicitly demonstrated by a calculation performed in the Rξ gauge. The gauge dependence of the AM's and NCR implies that they cannot be observed in isolation from other second-order, electroweak effects. It is shown, however, that the AM's of various hadronic systems having an SU(2)L quantum number TL3=0 can be considered ``observables'' in certain formal, though unphysical, limits. It is argued that, apart from these special limits, …

The (First) Three B’S Of The Skyrme Model, Alec Schramm

Alec J Schramm

No abstract provided.

Higgs Boson Production In Peripheral Heavy-Ion Collisions: Coherent Double-Pomeron Exchange, Alec Schramm, Berndt Muller

Alec J Schramm

Higgs boson production by coherent double-pomeron exchange in peripheral nuclear collisions at energies of several TeV per nucleon is calculated. It is shown that a trigger on quasi-elastic nuclear collisions strongly suppresses the cross section. The analogous two-photon process is predicted to dominate for collisions of heavy nuclei.

Digital-Image-Based Study Of Circular Holes In An Elastic Matrix, Anthony Day, K. Snyder, E. Garboczi, M. Thorpe

Anthony Roy Day

No abstract provided.

Solving Ill-Posed Problems With Artificial Neural Networks, Arun D. Kulkarni

Arun Kulkarni

Universal Conductivity Curve For A Plane Containing Random Holes., E. J. Garboczi, M. F. Thorpe, M. S. Devries, Anthony Roy Day

Anthony Roy Day

This paper examines the general percolation problem of cutting randomly centered insulating holes in a two-dimensional conducting sheet, and explores how the electrical conductivity sigma decreases with the remaining area fraction. This problem has been studied in the past for circular, square, and needlelike holes, using both computer simulations and analog experiments. In this paper, we extend these studies by examining cases where the insulating hole is of arbitrary shape, using digital-image-based numerical techniques in conjunction with the Y- [nabla] algorithm. We find that, within computational uncertainty, the scaled percolation threshold, xc=nc=5.9±0.4, is a universal quantity for all the cases …

Higgs-Boson Production In Peripheral Heavy-Ion Collisions: Electromagnetic Production, Alec Schramm, Burndt Muller

Alec J Schramm

Higgs-boson production via fusion of two virtual photons in nuclear collisions at energies of several TeV per nucleon is calculated. It is shown that although a trigger on quasielastic nuclear collisions suppresses the Higgs-boson production cross section, this mechanism could still provide a method for producing and detecting intermediate-mass Higgs bosons (MZ≲MH≲2MW).

On The Electrochemical Etching Of Tips For Scanning Tunneling Microscopy, Nancy Burnham, J. Ibe, P. Bey Jr., S. Brandow, R. Brizzolara, D. Dilella, K. Lee, C. K. Marrian, R. Colton

Nancy A. Burnham

The sharpness of tips used in scanning tunneling microscopy(STM) is one factor which affects the resolution of the STM image. In this paper, we report on a direct‐current (dc) drop‐off electrochemicaletching procedure used to sharpen tips for STM. The shape of the tip is dependent on the meniscus which surrounds the wire at the air–electrolyte interface. The sharpness of the tip is related to the tensile strength of the wire and how quickly the electrochemical reaction can be stopped once the wire breaks. We have found that the cutoff time of the etch circuit has a significant effect on the …

Atomistic Mechanisms And Dynamics Of Adhesion, Nanoindentation, And Fracture, Nancy Burnham, Uzi Landman, Wd Luedtke, Richard Colton

Nancy A. Burnham

Molecular dynamics simulations and atomic force microscopy are used to investigate the atomistic mechanisms of adhesion, contact formation, nanoindentation, separation, and fracture that occur when a nickel tip interacts with a gold surface. The theoretically predicted and experimentally measured hysteresis in the force versus tip-to-sample distance relationship, found upon approach and subsequent separation of the tip from the sample, is related to inelastic deformation of the sample surface characterized by adhesion of gold atoms to the nickel tip and formation of a connective neck of atoms. At small tipsample distances, mechanical instability causes the tip and surface to jump-to-contact, which …

Probing The Surface Forces Of Monolayer Films With An Atomic-Force Microscope, Nancy Burnham, Dawn Dominguez, Robert Mowery, Richard Colton

Nancy A. Burnham

Using an atomic force microscope (AFM), we have studied the attractive and adhesive forces between a cantilever tip and sample surfaces as a function of sample surface energy. The measured forces systematically increased with surface energy. The AFM is very sensitive; changes in the surface forces (i.e., attraction and adhesion) of monolayer covered samples could be clearly discerned when only the surface group of the monolayer film was changed from -CH3 to -CF3.

The Zero Momentum Limit Of The Vacuum Polarization At Finite Temperature, Ps Gribosky, Br Holstein

Barry R Holstein

We examine the zero momentum limit of the finite temperature vacuum polarization for a quantized scalar field coupled to a classical external field. Ordinarily, this type of Feynman diagram is plagued by nonanalytic behaviour when the external momentum tends to zero. Using imaginary-time, we show that this behaviour is not present in an exact background field solution and how the Feynman diagram calculation may be trivially modified to match the exact solution. Comparisons with recent real-time results are also made.

Radiative K13 Decays And Chiral Symmetry, Br Holstein

Barry R Holstein

No abstract provided.

Kaon Transitions And Predictions Of Chiral Symmetry, Jf Donoghue, Br Holstein

Barry R Holstein

We describe a set of kaonic electromagnetic and semileptonic weak decay processes which are completely predicted within the framework of chiral symmetry (and, therefore, of low-energy QCD), emphasizing where present problems exist and suggesting future experiments.

Conformal Transformations In Quantum Mechanics, Alec Schramm, Alfons Stahlhofen

Alec J Schramm

We discuss the occurrence of orientation- or area-preserving diffeomorphism groups in quantum mechanics. We show that the generators of these groups are contained in the generators of the symmetry group of a central potential, as is demonstrated by the example of the Coulomb problem. Our approach is based on the recently introduced concept of a factor space of scattering states.

Finite Temperature Effects In Na3+ And Na3: A Path Integral Monte Carlo Study, Randall W. Hall

Randall W. Hall

Pitch Of Complex Tones With Many High‐Order Harmonics, Adrianus J. M. Houtsma, J. Smurzynski

Jacek Smurzynski

The Adiabatic Propagator, Br Holstein

Barry R Holstein

The Feynman propagator is expanded in the adiabatic limit, wherein the time scale over which the potential varies is long compared to typical quantum mechanical oscillation times in the problem. Comparison with known exact results is made for two simple models.

Rigidity Percolation, Anthony Day, M. Thorpe, W. Xia

Anthony Roy Day

No abstract provided.

The Adiabatic Theorem And Berry's Phase, Br Holstein

Barry R Holstein

A study is presented of Berry's observation that when a quantum-mechanical system is transported on a closed adiabatic journey, a topological phase arises in addition to the usual dynamical phase expected from the adiabatic theorem. Consequences are explored in the case of a simple magnetic moment-magnetic field interaction and are shown to lead, among other things, to Dirac's famous relation between electric and magnetic charges.

Random Elastic Networks, Anthony Day, M. Thorpe, W. Xia

Anthony Roy Day

Proceedings of the International Workshop on Condensed Matter Theories, 1988.

Constraints On Left-Right-Symmetric Models From Neutron Decay, As Carnoy, J Deutsch, Br Holstein

Barry R Holstein

The implications for left-right-symmetric models of recent neutron-β-decay asymmetry and lifetime measurements are analyzed. The significance of forthcoming high-precision lifetime measurements is stressed.

Ab Initio Approach To The Deuteron In The Skyrme-Witten Model, Alec Schramm

Alec J Schramm

No abstract provided.

A Calculation Of The Deuteron As A Biskyrmion, Alec Schramm, Yossef Dothan, L. Beidenharn

Alec J Schramm

No abstract provided.

Gauge-Invariance And Quantization, Br Holstein

Barry R Holstein

Quantizing theories such as quantum electrodynamics that contain a gauge invariance are discussed via a simple pedagogical example. Canonical and path integral quantization methods are compared.

Semiclassical Treatment Of The Double Well, Br Holstein

Barry R Holstein

The double well potential V(x)= 1/4 λ(x2-α2)2 is addressed using both semiclassical path integral and instanton techniques. The basic physics of the two-state system is shown to arise, and energy levels calculated via the two methods are compared.

Comment On "Percolation In Isotropic Elastic Media.", Anthony Day, M. Thorpe

Anthony Roy Day

No abstract provided.

Spectral Dimensionality Of Random Superconducting Networks, Anthony Roy Day, W. Xia, M. F. Thorpe

Anthony Roy Day

We compute the spectral dimensionality d-tilde of random superconducting-normal networks by directly examining the low-frequency density of states at the percolation threshold. We find that d-tilde=4.1±0.2 and 5.8±0.3 in two and three dimensions, respectively, which confirms the scaling relation d-tilde=2d/(2-s/ nu ), where s is the superconducting exponent and nu the correlation-length exponent for percolation. We also consider the one-dimensional problem where scaling arguments predict, and our numerical simulations confirm, that d-tilde=0. A simple argument provides an expression for the density of states of the localized high-frequency modes in this special case. We comment on the connection between our calculations …

Stability Of Networks Under Tension And Pressure, Anthony Roy Day, H. Yan, M. F. Thorpe

Anthony Roy Day

The number of zero-frequency modes of an elastic network is an important quantity in determining the stability of the network. We present a constraint-counting method for finding this number in general central-force networks that are under an external tension. The technique involves isolating the backbone and then counting constraints in the same way as for free standing networks. A detailed example of this counting is given for a random two-dimensional network subject to an external tension. The results are shown to agree with the number of zero-frequency modes as determined by a direct matrix diagonalization.

Electron Beam Effects In The Analysis Of Compound Semiconductors And Devices, Nancy Burnham, Ll Kazmerski, Ab Swartzlander, Aj Nelson, Se Asher

Nancy A. Burnham

The effects of electron beams on the analysis of CuInSe2surfaces are examined in this paper. Potential changes in the surface chemistry—including oxidation and desorption—under a range of incident probe conditions, are investigated for possible artifactual information generation. Emphasis is placed on the relationships between beam conditions and oxygen chemisorption and physisorption, since oxygen treatments of devices utilizing this semiconductor are critical to performance. Single crystals and polycrystalline thin films are analyzed and compared to establish the beam‐induced phenomena.

Cp Violation In K-]3-Pi, Jf Donoghue, Br Holstein, G Valencia

Barry R Holstein

No abstract provided.