Showing papers on "Symmetry (physics) published in 1983"
Book•
01 Jan 1983
TL;DR: In this paper, the idea of the renormalization group in many-body physics broken symmetry topology Bose systems quantum solids renormalisation group was introduced. But the renationalization group was not used in quantum physics broken-symmetric topology.
Abstract: Basic principles I - broken symmetry basic principles II - adiabatic continuity and renormalization solids, quantum and otherwise uses of the idea of the renormalization group in many-body physics broken symmetry topology Bose systems quantum solids renormalization group.
809 citations
TL;DR: In this article, the existence of fermions can cause dynamical instability of a vacuum at low energies by quantum effects, even if they are massless at the tree level.
790 citations
TL;DR: In this paper, the anisotropy of the laser-induced fluorescence is given explicitly in terms of the zeroth, second, and fourth rank moments of the angular momentum distribution, which, respectively, are proportional to the population, quadrupole alignment, and hexadecapole alignment of the product internal state under study.
Abstract: For collision systems having axial symmetry, the anisotropy of the laser‐induced fluorescence is given explicitly in terms of the zeroth, second, and fourth rank moments of the angular momentum distribution, which, respectively, are proportional to the population, the quadrupole alignment, and hexadecapole alignment of the product internal state under study. Expressions are presented for determining these three quantities from the dependence of the fluorescence intensity on the polarizations of the absorbed and detected photons. Results are presented for an arbitrary excitation‐detection geometry which is then specialized to the commonly occurring cases where the direction of fluorescence detection is at right angles to the axis of cylindrical symmetry and the direction of the incoming light beam is either along the axis of cylindrical symmetry or at right angles to it and to the fluorescence detection direction. The approach of these expressions to the high‐J limit is considered. The effect of nuclear spin on the fluorescence intensity is analyzed and the extent of depolarization is shown to be unimportant for large J. The use of angular momentum recoupling algebra permits the geometrical and dynamical aspects of this problem to be completely disentangled.
332 citations
TL;DR: The second-harmonic reflection from Si(100 and Si(111) surfaces exhibits a strong dependence on the angle of rotation of the sample about its surface normal as discussed by the authors, which can be related directly to the structural symmetry of the crystal and of the surface.
Abstract: Second-harmonic reflection from Si(100) and Si(111) surfaces exhibits a strong dependence on the angle of rotation of the sample about its surface normal. This behavior can be related directly to the structural symmetry of the crystal and of the surface. Analysis of the results shows that the surface and bulk contributions to the observed second-harmonic signals from Si are generally of the same order of magnitude.
306 citations
TL;DR: In this article, the Susskind fermionic action is expressed explicitly in terms of flavour Dirac fields defined on hypercubes in position space, and the decay constant of the pseudo-scalar Goldstone boson associated with spontaneous breakdown of the U(1) A symmetry is derived.
206 citations
TL;DR: In this paper, the S-wave phase shifts were calculated using the resonating group method, which yields a hard-core phase shift for the singlet and triplet S-waves.
196 citations
TL;DR: In this paper, a generation mechanism of the quark and lepton masses in gauge models with horizontal symmetry is proposed, based on the mixing of quark-lepton families with heavy horizontal fermions, acquiring large masses directly after breaking of horizontal symmetry.
188 citations
TL;DR: In this paper, the Yang-Mills theory and simple supergravity in seven dimensions were constructed and the potential for the scalar field φ is of the form exp(φ) and has no extremum.
162 citations
TL;DR: In this paper, a quantum mechanical method based on the Kramers-Heisenberg dispersion relation is used to evaluate the dielectric response of small metal particles, and thereby to determine the influence of particle size on the widths of the plasmon resonance line shapes.
Abstract: A quantum mechanical method based on the Kramers–Heisenberg dispersion relation is used to evaluate the dielectric response of small metal particles, and thereby to determine the influence of particle size on the widths of the plasmon resonance line shapes. Several different particle shapes are considered (sphere, cylinder, rectangular prism, spherical shell, and cylindrical shell) and for each shape a free electron Schrodinger equation is used to determine conduction band energies and dipole matrix elements. The main emphasis in this work is on particle sizes large enough that only the first order deviations from the infinite size limit are important, and for such sizes we find that the size dependent contribution to the width can be expressed in terms of an effective length Leff. This effective length is found to depend on the direction of the external field relative to the particle symmetry axes, and on the shape of the particle. For compact shapes, Leff is accurately approximated by 0.65 Lav along eac...
156 citations
TL;DR: The existence of periodic orbits for Hamiltonian systems at low positive energies can be deduced from the existence of non-degenerate critical points of an averaged Hamiltonian on an associated reduced space as mentioned in this paper.
114 citations
TL;DR: In this article, the fermion-boson composite model was used to estimate the masses and flavor mixing angles of quarks and lepton masses and their associated flavor mixing angle in 3 × 3* = 8 + 1 of the SU(3)-generation symmetry.
TL;DR: Goodman as mentioned in this paper proposed a class of diagonals-parameter symmetry models for square contingency tables with ordered categories, a simple version of that model is considered in which the log odds parameters have a linear pattern.
TL;DR: The Fermi-Bose symmetry as discussed by the authors is the only way of combining internal symmetries with Lorentz invariance in our 4 dimensional space-time, and is also expected to be useful for understanding the existence of massless fermions in terms of a well-defined geometry.
TL;DR: In this article, the exact solutions of the many-dimensional nonlinear d'Alembert, Liouville, sine-Gordon and eikonal equations are obtained and the maximally extensive local invariance groups of the equations are determined.
Abstract: Multiparametrical exact solutions of the many-dimensional nonlinear d'Alembert, Liouville, sine-Gordon and eikonal equations are obtained. The maximally extensive local invariance groups of the equations are determined and invariants of the extended Poincare group are found.
TL;DR: In this paper, an extensive numerical investigation of the dynamics of the driven damped pendulum is conducted and the authors find broad bands of chaotic solutions as a function of the frequency and amplitude of the driving force.
Abstract: The equation of motion of the driven damped pendulum is related at low dissipation to a current-fed Josephson junction and at high dissipation to transport in charge-density-wave (CDW) systems. We report on an extensive numerical investigation of these equations. At low dissipation we find broad bands of chaotic solutions as a function of the frequency and amplitude of the driving force. It is pointed out that periodic solutions may possess a symmetry corresponding to the invariance of the equations of motion under a simultaneous spatial (phase) inversion and a shift in the phase of the driving force by an odd multiple of $\ensuremath{\pi}$. At low dissipation chaos is usually approached via a sequence of period-doubling bifurcations if this symmetry has been broken and directly from period 1 with associated intermittency behavior if the symmetry is not broken. At high dissipation no chaotic behavior is found but broad bands of symmetry-broken solutions, which may be related to recently reported hysteresis phenomena in CDW systems, occur. Discussions of properties of the Poincar\'e maps and of the fractal dimension of the strange attractors associated with the chaotic solutions have been included.
TL;DR: In this paper, the authors discuss the possibility of generating small Dirac neutrino masses in a natural way, and give a mechanism based on symmetry arguments which works in the SU(2) × U(1) and SU(5) models, but fails in left-right symmetric theories.
TL;DR: In this article, the authors show that the long lifetime of ν2 is due to the absence of anharmonic interaction to neighboring states (symmetry forbidden), and the corresponding CC•stretching mode of C6H5−C2H has a lifetime of 15 ps.
Abstract: The excitation of the CH‐stretching mode (ν3) of C2H2 in CCl4 leads to fast population (<2 ps) and very slow depopulation (240 ps) of the symmetric CC‐stretching mode (ν2). The long lifetime of ν2 is due to the absence of anharmonic interaction to neighboring states (symmetry forbidden). The corresponding CC‐stretching mode of C6H5–C2H has a lifetime of 15 ps. The phenyl group relaxes the symmetry restrictions and introduces new decay channels.
TL;DR: In this paper, two distinct realizations of SU(3) symmetry, the Gell-Mann symmetry in quark physics and the Elliott symmetry in nuclear physics, can be applied to the same dynamical system in intense-field electrodynamics under different experimental conditions.
Abstract: We show that two distinct realizations of the SU(3) symmetry---the Gell-Mann SU(3) symmetry in quark physics and the Elliott SU(3) symmetry in nuclear physics---can be applied to the same dynamical system in intense-field electrodynamics under different experimental conditions. We also present a set of simultaneous soliton solutions in the Elliott SU(3)-symmetry scheme which has not been derived previously.
TL;DR: In this article, the chemical origin of symmetry breaking was analyzed using a simple valence bond picture and the lowest 3A2 and 3B2 states of CO2 as examples, which provided the necessary information to design MCSCF wave functions which possessed the symmetry of the nuclear frame and changed smoothly between high and low symmetry nuclear configurations.
Abstract: A general, orthogonal orbital, multiconfuguration self‐consistent field (MCSCF) plus configuration interaction (CI) procedure has been developed for treating open shell molecules subject to symmetry breaking (doublet instability, etc.) in the restricted Hartree–Fock approximation. The chemical origin of symmetry breaking was analyzed using a simple valence bond picture and the lowest 3A2 and 3B2 states of CO2 as examples. This analysis provided the necessary information to design MCSCF wave functions which possessed the symmetry of the nuclear frame, and changed smoothly between high and low symmetry nuclear configurations. Near qualitative potential energy surfaces near the potential minima of the two lowest triplet states of CO2 were obtained by CI calculations using the MCSCF orbitals and reference configurations. Both states were found to have C2v potential minima with the 3A2 state lying approximately 0.9 eV above the 3B2 state. The equilibrium CO bond lengths and OCO bond angles are 1.24 A, 118° and...
TL;DR: In this article, the scattering coefficient and the phase and group velocities of plane shear waves in polycrystals of cubic symmetry with randomly orientated grains were calculated in second-order perturbation theory using the assumption that the changes in the elastic constants and in the density from grain to grain are small.
Abstract: The theory of ultrasonic propagation in polycrystals presented in a previous paper is used to calculate the scattering coefficient and the phase and group velocities of plane shear waves in polycrystals of cubic symmetry with randomly orientated grains. The calculation was done in second‐order perturbation theory using the assumption that the changes in the elastic constants and in the density from grain to grain are small. The asymptotic values at low κa (Rayleigh scattering) are exactly the same as the well‐known results from Bhatia and Moore. Numerical calculations are carried out for some examples.
TL;DR: In this article, the basic features of the magnetic structures of LaTiO3 and CeTiO 3 were determined by powder neutron diffraction and the most consistent interpretation is to assign G-type configuration to Ti(III) and an induced Fz on Ce(III).
TL;DR: In this paper, the sign of the matrix element of a symmetry operator between Bogoliubov states is determined, and the numerical effect of the sign on the numerical function is discussed.
TL;DR: In this paper, the authors present observations of second-harmonic generation in Si and argue that under intense laser excitation inversion symmetry is broken, and dipolar bulk second harmonic generation becomes possible.
Abstract: We present observations of second-harmonic generation in Si and argue that under intense laser excitation inversion symmetry is broken, and dipolar bulk second-harmonic generation becomes possible. A mechanism is proposed for removing inversion symmetry in higly excited Si.
TL;DR: In this paper, minimal electromagnetic coupling schemes entering into Klein-Gordon or Schrodinger equations are studied in connection with symmetries outside the symmetry groups of the corresponding free equations.
Abstract: Minimal electromagnetic coupling schemes entering into Klein–Gordon or Schrodinger equations are studied in connection with symmetries outside the symmetry groups of the corresponding free equations. The Schrader construction of the so‐called (relativistic) Maxwell group is reviewed through group extensions of kinematical groups associated with (constant and uniform) electromagnetic fields. The construction of the Galilean (nonrelativistic) Maxwell group is given.
TL;DR: In this article, the authors studied the magnetic field near the null of a two-dimensional magnetic field and found that the magnetic moment is invariant to the number of degrees of freedom in the system, e and σ (the sign of pz ).
Abstract: Charged particle motion near the null of a two‐dimensional magnetic field is studied. Specifically, the magnetic field is given by the vector potential A=zψ0[(y/a)2+(ex/a)2], in which ψ0,a, and e are constants with e parameterizing the ellipticity of the flux surfaces. Conservation of canonical z momentum pz reduces the number of nontrivial degrees of freedom to two. Scaling reduces the number of parameters in the system to two, e and σ (the sign of pz ). Analytical and numerical methods are used to study the nature of orbits. The results are expressed conveniently in terms of e and Q≡(2mE)1/2/pz. When e is unity, the additional symmetry implies integrability. When e is less than unity (the case e>1 is trivially related) three regimes are found: (1) For ‖Q‖≫1 particle orbits are regular, (2) for e3/2≲‖Q‖≲1 most particle orbits are stochastic, and (3) for ‖Q‖≪e3/2 particle orbits are regular, with the third invariant being the magnetic moment.
TL;DR: In this paper, a bunch of charged particles passing an accelerating cavity or any other structure of varying shape excites electromagnetic fields that act back on the particles, and the net change in momentum due to such fields is obtained by an integration over all times during which the fields interact with the particles.
TL;DR: In this article, a self-consistent field approximation allowing for a change of coordinates is applied to a model of two coupled oscillators considered by Davis and Heller [J. Chem. Phys. 75, 246 (1981)].
Abstract: A self-consistent field approximation allowing for a change of coordinates is applied to a model of two coupled oscillators considered by Davis and Heller [J. Chem. Phys. 75, 246 (1981)]. The model accounts well for the unsymmetrical nonstationary states involved in the quantum dynamical tunneling phenomenon.