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Showing papers in "Physical Review Letters in 1979"


Journal ArticleDOI
TL;DR: In this paper, the authors present a theoretical study of soliton formation in long-chain polyenes, including the energy of formation, length, mass, and activation energy for motion.
Abstract: We present a theoretical study of soliton formation in long-chain polyenes, including the energy of formation, length, mass, and activation energy for motion. The results provide an explanation of the mobile neutral defect observed in undoped ${(\mathrm{CH})}_{x}$. Since the soliton formation energy is less than that needed to create band excitation, solitons play a fundamental role in the charge-transfer doping mechanism.

4,562 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the conductance of disordered electronic systems depends on their length scale in a universal manner, and asymptotic forms for the scaling function were obtained for both two-dimensional and three-dimensional systems.
Abstract: Arguments are presented that the $T=0$ conductance $G$ of a disordered electronic system depends on its length scale $L$ in a universal manner. Asymptotic forms are obtained for the scaling function $\ensuremath{\beta}(G)=\frac{d\mathrm{ln}G}{d\mathrm{ln}L}$, valid for both $G\ensuremath{\ll}{G}_{c}\ensuremath{\simeq}\frac{{e}^{2}}{\ensuremath{\hbar}}$ and $G\ensuremath{\gg}{G}_{c}$. In three dimensions, ${G}_{c}$ is an unstable fixed point. In two dimensions, there is no true metallic behavior; the conductance crosses over smoothly from logarithmic or slower to exponential decrease with $L$.

4,466 citations


Journal ArticleDOI
TL;DR: In this paper, an intense electromagnetic pulse can create a weak of plasma oscillations through the action of the nonlinear ponderomotive force, and electrons trapped in the wake can be accelerated to high energy.
Abstract: An intense electromagnetic pulse can create a weak of plasma oscillations through the action of the nonlinear ponderomotive force. Electrons trapped in the wake can be accelerated to high energy. Existing glass lasers of power density ${10}^{18}$W/${\mathrm{cm}}^{2}$ shone on plasmas of densities ${10}^{18}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ can yield gigaelectronvolts of electron energy per centimeter of acceleration distance. This acceleration mechanism is demonstrated through computer simulation. Applications to accelerators and pulsers are examined.

3,867 citations


Journal ArticleDOI
TL;DR: In this article, a simple procedure to extract pseudopotentials from ab initio atomic calculations is presented, which yield exact eigenvalues and nodeless eigenfunctions which agree with atomic wave functions beyond a chosen radius.
Abstract: A very simple procedure to extract pseudopotentials from ab initio atomic calculations is presented. The pseudopotentials yield exact eigenvalues and nodeless eigenfunctions which agree with atomic wave functions beyond a chosen radius ${\mathcal{r}}_{c}$. Moreover, logarithmic derivatives of real and pseudo wave functions and their first energy derivatives agree for $\mathcal{r}g{\mathcal{r}}_{c}$ guaranteeing excellent transferability of the pseudopotentials.

2,947 citations


Journal ArticleDOI
TL;DR: In this article, a weak-interaction singlet heavy quark and a new scalar meson are predicted, and a very light axion is shown to have strong CP invariance.
Abstract: Strong $\mathrm{CP}$ invariance is automatically preserved by a spontaneously broken chiral ${\mathrm{U}(1)}_{4}$ symmetry. A weak-interaction singlet heavy quark $Q$, a new scalar meson ${\ensuremath{\sigma}}^{0}$, and a very light axion are predicted. Phenomenological implications are also included.

2,267 citations


Journal ArticleDOI
TL;DR: In this paper, a number of properties of possible baryon and lepton-nonconserving processes are shown under very general assumptions, and the importance of measuring the polarizations and ratios in nucleon decay as a means of discriminating among specific models is discussed.
Abstract: A number of properties of possible baryon- and lepton-nonconserving processes are shown to follow under very general assumptions. Attention is drawn to the importance of measuring ${\ensuremath{\mu}}^{+}$ polarizations and $\frac{{\overline{\ensuremath{ u}}}_{e}}{{e}^{+}}$ ratios in nucleon decay as a means of discriminating among specific models.

1,746 citations


Journal ArticleDOI
TL;DR: In this paper, a comparison was made between four low-temperature properties of LaCu2Si2 and CeCu2 Si2 and it was shown that superconductivity can exist in a metal in which many-body interactions, probably magnetic in origin, have strongly renormalized the properties of the conduction-elec-tron gas.
Abstract: A comparison was made between four low-temperature properties of LaCu2Si2and CeCu2Si2. Whereas LaCu2Si2behaves like a normal metal, CeCu2Si2shows (i) low-temperature anomalies typical of “unstable 4f shell” behavior and (ii) a transition into a superconducting state atT c ≃ 0.5 K. Our experiments demonstrate for the first time that superconductivity can exist in a metal in which many-body interactions, probably magnetic in origin, have strongly renormalized the properties of the conduction-elec-tron gas.

1,626 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that the path-integral measure for gauge-invariant fermion theories is not invariant under the ε-ensuremath{gamma{5}$ transformation and the Jacobian gives rise to an extra phase factor corresponding to the Adler-Bell-Jackiw anomaly.
Abstract: It is shown that the path-integral measure for gauge-invariant fermion theories is not invariant under the ${\ensuremath{\gamma}}_{5}$ transformation and the Jacobian gives rise to an extra phase factor corresponding to the Adler-Bell-Jackiw anomaly. The derivation of "anomalous" Ward-Takahashi identities by means of the variational derivative can thus be made consistent in the path-integral formalism.

1,101 citations


Journal ArticleDOI
TL;DR: In this article, the energy spectrum of electrons produced by multiphoton ionization of xenon atoms has been analyzed with a retarding potential technique, and it has been shown that the discrete absorption of photons above the six-photon ionization threshold was observable under specified conditions.
Abstract: The energy spectrum of electrons produced by multiphoton ionization of xenon atoms has been analyzed with a retarding potential technique. We have shown that the discrete absorption of photons above the six-photon ionization threshold was observable under specified conditions. A simple model based upon inverse bremsstrahlung gives a resonable agreement with the experiments.

1,076 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that in the mean-field approximation spin-glasses must be described by an infinite number of order parameters in the framework of replica theory, and that the number of parameters is infinite.
Abstract: This Letter shows that in the mean-field approximation spin-glasses must be described by an infinite number of order parameters in the framework of the replica theory.

909 citations


Journal ArticleDOI
TL;DR: In this article, the Vlasov equation was used to show that massive galactic halos cannot be composed of stable neutral leptons of mass ≤ 1 MeV (e.g., muon or electron neutrinos).
Abstract: Using the Vlasov equation, we show that massive galactic halos cannot be composed of stable neutral leptons of mass \ensuremath{\lesssim} 1 MeV. Since most of the mass in clusters of galaxies probably consists of stripped halos, we conclude that the "missing mass" in clusters does not consist of leptons of mass \ensuremath{\lesssim} 1 MeV (e.g., muon or electron neutrinos). Lee and Weinberg's hypothetical heavy leptons (mass \ensuremath{\lesssim} 1 GeV) are not ruled out by this argument.

Journal ArticleDOI
D. J. Chadi1
TL;DR: In this article, the optimal 2-ifmmode-times-else-texttimes-fi{}1 and 4-ifmodes-times−texttimes−fi{2 reconstructed surfaces of Si determined from energy-minimization claculations are presented.
Abstract: New structural models for 2\ifmmode\times\else\texttimes\fi{}1 and 4\ifmmode\times\else\texttimes\fi{}2 reconstructed (100) surfaces of Si determined from energy-minimization claculations are presented. The optimal 2\ifmmode\times\else\texttimes\fi{}1 and 4\ifmmode\times\else\texttimes\fi{}2 structures are found to correspond to asymmetric dimer geometries with partially ionic bonds between surface atoms, resulting in semiconducting surface electronic bands. The atomic and electronic structures for the 2\ifmmode\times\else\texttimes\fi{}1 and 4\ifmmode\times\else\texttimes\fi{}2 reconstructed surfaces are discussed.

Journal ArticleDOI
TL;DR: In this paper, it was shown that in the absence of a magnetic field, the hidden supersymmetry of the associated stochastic differential equation (SDE) can be overcome.
Abstract: We prove the equivalence, near the critical point, of a $D$-dimensional spin system in a random external magnetic field with a ($D\ensuremath{-}2$)-dimensional spin system in the absence of a magnetic field. This is due to the hidden supersymmetry of the associated stochastic differential equation. We identify a space with one anticommuting coordinate with a space having negative dimensions -2.

Journal ArticleDOI
C. C. Grimes1, G. Adams1
TL;DR: In this paper, an electron-liquid to electron-crystal phase transition in a sheet of electrons on a liquid-He surface has been shown to occur at a temperature between 0.35 and 0.65 K.
Abstract: Experimental evidence is presented for an electron-liquid to electron-crystal phase transition in a sheet of electrons on a liquid-He surface. The phase transition has been studied for electron areal densities from 3\ifmmode\times\else\texttimes\fi{}${10}^{8}$ ${\mathrm{cm}}^{\ensuremath{-}2}$ to 9\ifmmode\times\else\texttimes\fi{}${10}^{8}$ ${\mathrm{cm}}^{\ensuremath{-}2}$ and has yielded melting temperatures between 0.35 and 0.65 K. The phase transition occurs at $\ensuremath{\Gamma}=137\ifmmode\pm\else\textpm\fi{}15$, where $\ensuremath{\Gamma}$ is a measure of the ratio of potential energy to kinetic energy per electron.

Journal ArticleDOI
John Preskill1
TL;DR: In this paper, the phase transition at the grand unification mass scale is strongly first order and the density of superheavy magnetic monopoles in the early universe is estimated to be unacceptably large.
Abstract: Grand unified models of elementary particle interactions contain stable superheavy magnetic monopoles. The density of such monopoles in the early universe is estimated to be unacceptably large. Cosmological monopole production may be suppressed if the phase transition at the grand unification mass scale is strongly first order.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the resulting baryon to entropy ratio can be calculated in terms of purely microscopic quantities, and it was further shown that such a ratio can also be calculated for the case when baryons are violated by processes that violate baryone number conservation.
Abstract: Departures from thermal equilibrium which are likely to occur in an expanding universe allow the production of an appreciable net baryon density by processes which violate baryon-number conservation. It is shown that the resulting baryon to entropy ratio can be calculated in terms of purely microscopic quantities.

Journal ArticleDOI
TL;DR: In this paper, a model of a monolayer of atoms adsorbed on a crystalline surface is discussed, and the spectrum of small oscillations has two acoustic branches, one vanishing at the phase transition.
Abstract: A model of a monolayer of atoms adsorbed on a crystalline surface is discussed. When the initial incommensurability, $\ensuremath{\delta}$, between a reciprocal lattice vector of the monolayer and one of the substrate is small, the monolayer has a one-dimensional superstructure with period depending on $\ensuremath{\delta}$. For $\ensuremath{\delta}g{\ensuremath{\delta}}_{c}(T)$ the state is incommensurate; ${\ensuremath{\delta}}_{c}(T)$ decreases and vanishes at a ${T}_{c}$ given by the elastic moduli of the monolayer. The spectrum of small oscillations has two acoustic branches, one vanishing at the phase transition.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the nature of wave functions and eigenvalues when the short-wave-limit Hamiltonian has stochastic trajectories, and the eigenfunctions exhibit a random pattern for the nodal curves, with isotropic distribution of local wave vectors.
Abstract: Quantum stochasticity (the nature of wave functions and eigenvalues when the short-wave-limit Hamiltonian has stochastic trajectories) is studied for the two-dimensional Helmsholtz equation with "stadium" boundary. The eigenvalue separations have a Wigner distribution (characteristic of a random Hamiltonian), in contrast to the clustering found for a separable equation. The eigenfunctions exhibit a random pattern for the nodal curves, with isotropic distribution of local wave vectors.

Journal ArticleDOI
TL;DR: A theory of gravity incorporating the concept of spontaneous symmetry breaking is proposed in this article, where it is suggested that the same symmetry-breaking mechanism is responsible for breaking a unified gauge theory into strong, weak, and electromagnetic interactions.
Abstract: A theory of gravity incorporating the concept of spontaneous symmetry breaking is proposed. It is suggested that the same symmetry-breaking mechanism is responsible for breaking a unified gauge theory into strong, weak, and electromagnetic interactions.

Journal ArticleDOI
TL;DR: In this paper, the possible existence of a Kosterlitz-thouless vortex-antivortex dissociation transition in thin superconducting films is discussed and it is found that in practice the situation should be closely analogous to that predicted for superfluid-helium films.
Abstract: The possible existence of a Kosterlitz-Thouless vortex-antivortex dissociation transition in thin superconducting films is discussed. It is found that in practice the situation should be closely analogous to that predicted for superfluid-helium films. A simple relationship is found between the Kosterlitz-Thouless transition temperature and the sheet resistance. This relationship is compared with the observed broadening of the resistive transition of superconducting films with high sheet resistance.

Journal ArticleDOI
TL;DR: In this article, a kinship hypothesis important in analyzing nucleon decay is formulated and tests of it are proposed, and selection rules diagnostic of the underlying superunified theories are derived.
Abstract: The operator structure of the effective Hamiltonian mediating nucleon decay is analyzed. Selection rules diagnostic of the underlying superunified theories are derived. A kinship hypothesis important in analyzing nucleon decay is formulated and tests of it are proposed.

Journal ArticleDOI
TL;DR: In this article, the authors introduced the idea of an incoherence length at which inelastic collision broadening equals electronic energy-level separation and showed that the two-dimensional conductance cross over at this length from a $\mathrm{ln}L$ dependence suggested by Abrahams et al. to Ohmic behavior.
Abstract: We introduce the idea of an incoherence length ${L}_{2}$ at which inelastic collision broadening equals electronic energy-level separation. The two-dimensional conductance crosses over at ${L}_{2}$ from a $\mathrm{ln}L$ dependence suggested recently by Abrahams et al. to Ohmic behavior. These ideas and plausible relaxation and heating models are used to explain the nonlinear conductivity observations of Dolan and Osheroff.

Journal ArticleDOI
TL;DR: In this article, the effect of Earth's rotation on the phase of the neutron wave function was observed using a neutron interferometer of the type first developed by Bonse and Hart for x rays.
Abstract: Using a neutron interferometer of the type first developed by Bonse and Hart for x rays, we have observed the effect of Earth's rotation on the phase of the neutron wave function. This experiment is the quantum mechanical analog of the optical interferometry observations of Michelson, Gale, and Pearson.

Journal ArticleDOI
TL;DR: In this article, the authors studied pure SU(2) gauge fields in four and five space-time dimensions and a compact SO(2)-gauge field in four dimensions.
Abstract: Using Monte Carlo techniques, we study pure SU(2) gauge fields in four and five space-time dimensions and a compact SO(2) gauge field in four dimensions. Ultraviolet divergences are regulated with Wilson's lattice prescription. Both SU(2) in five dimensions and SO(2) in four dimensions show clear phase transitions between the confining regime at strong coupling and a spin-wave phase at weak coupling. No phase change is seen for the four-dimensional SU(2) theory.

Journal ArticleDOI
TL;DR: In this article, the densities of hydrogen molecules were measured in low-pressure plasmas by photodetachment to confirm and extend previous work done with probes, showing no isotope dependence.
Abstract: ${\mathrm{H}}^{\ensuremath{-}}$ and ${\mathrm{D}}^{\ensuremath{-}}$ densities are measured in low-pressure plasmas by photodetachment to confirm and extend previous work done with probes. Measurements indicate no isotope dependence, with ${n}_{\ensuremath{-}}$ rising in proportion to ${{n}_{e}}^{3}$ in the density range below ${n}_{e}={10}^{10}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. This functional dependence is consistent with ${\mathrm{H}}^{\ensuremath{-}}$ production by a nonlinear process such as dissociative attachment to excited hydrogen molecules and ${\mathrm{H}}^{\ensuremath{-}}$ loss by diffusion.

Journal ArticleDOI
TL;DR: In this article, it is suggested that odd-A$A$ nuclei be treated as a system of interacting bosons and fermions and that a simple choice for the form of the boson-fermion interaction is sufficient to describe the variety of observed spectra.
Abstract: It is suggested that odd-$A$ nuclei be treated as a system of interacting bosons and fermions. It is shown that a simple choice for the form of the boson-fermion interaction is sufficient to describe the variety of observed spectra.

Journal ArticleDOI
TL;DR: In this article, the positions of quantized vortex lines in rotating superfluid helium have been recorded using a photographic technique, and the observed patterns are in good agreement with theoretical predictions.
Abstract: The positions of quantized vortex lines in rotating superfluid helium have been recorded using a photographic technique. The photographs show stationary arrays of vortices. The observed patterns are in good agreement with theoretical predictions.

Journal ArticleDOI
TL;DR: In this article, non-leading QCD corrections to e+e- annihilation into hadrons are computed and comparison with experiment is briefly discussed, and compared with experiment with experiment.
Abstract: Nonleading QCD corrections to e+e- annihilation into hadrons are computed. Comparison with experiment is briefly discussed.

Journal ArticleDOI
TL;DR: In this article, the quantum spin-textonehalf{} Heisenberg antiferromagnet in one dimension with randomly distributed coupling constants is solved approximately, and groundstate energies and low-temperature properties are obtained for several distributions of coupling constants (including both singular and nonsingular distributions).
Abstract: The quantum spin-\textonehalf{} Heisenberg antiferromagnet in one dimension with randomly distributed coupling constants is solved approximately. Ground-state energies and low-temperature properties are obtained for several distributions of coupling constants (including both singular and nonsingular distributions). Power-law temperature dependence in specific heat and in susceptibility are found for all distributions studied.

Journal ArticleDOI
TL;DR: In this paper, the chemical structure of thin Si${\mathrm{O}}_{2}$ films and Si${O}$-Si interfaces has been investigated using high-resolution x-ray photoelectron spectroscopy.
Abstract: The chemical structure of thin Si${\mathrm{O}}_{2}$ films and Si${\mathrm{O}}_{2}$-Si interfaces has been investigated using high-resolution x-ray photoelectron spectroscopy. The data are consistent with a continuous random network of four-, six-, seven-, and eight-member rings of Si${\mathrm{O}}_{4}$ tetrahedra joined together by bridging oxygens. This distribution changes substantially within 30 \AA{} of the Si${\mathrm{O}}_{2}$-Si interface. The near-interface region is comprised of ${\mathrm{Si}}_{2}$${\mathrm{O}}_{3}$, SiO, and ${\mathrm{Si}}_{2}$O. This structure is interpreted by means of a structure-induced-charge-transfer model.