The characteristic lengths associated with the flux-flow resistance and with the critical fields measured at the vortex-antivortex transition temperature of thin-film $\mathrm{In}/\mathrm{In}{\mathrm{O}}_x$ composites have been found to be approximately equal and to diverge simultaneously near critical disorder where superconductivity disappears. The observed disorder-induced enhancement of the vortex mobility cannot be explained by the dirty-limit formula for the coherence length when used within the context of the Bardeen-Stephen description for vortex dissipation.

A new and simple rate expression incorporating mutual interaction between reactants is presented within the framework of absolute-reaction-rate theory. The expression is derived by applying a simplified model of the lattice-gas Hamiltonian and working with it in the molecular-field approximation. Applications to the results of zero-order desorption spectra occurring in isothermal- and thermal-desorption measurements are discussed. Direct extension of the present results to the general inhomogeneous reactions suggests that the reaction rate would be zero order whenever an adsorptive reactant system is in the two-phase or multiphase coexistence region.

The time evolution of the $N$-vector model coupled to the Einstein field equation in a Robertson-Walker metric is studied numerically under the assumption of initial equilibrium at high temperatures and in the limit as $N\to \infty$. The system shows inflationary expansion of the Robertson-Walker scale factor, $a\left(t\right)\mathrm{}$, over many $e$-foldings as well as local ordering. The associated structure factor develops a Bragg peak near zero wave number which has the proper weight for a spontaneously broken symmetry and has a width (inversely proportional to a characteristic domain size) which is inversely proportional to $a\left(t\right)\mathrm{}$.

We report successful operation of a neutron microscope using ultracold neutrons at the high-flux reactor at Grenoble. A sharp, achromatic image of an object slit was obtained at a magnification of 50. The measured resolution of 0.1 mm was limited mainly by the available beam intensity, not by aberrations.

A simple method is used to calculate the currents induced by static uniform electromagnetic fields in the ground state of a two-dimensional electron gas. This is done for both the relativistic and the nonrelativistic cases. This analysis is used to explain the apparent similarity between the anomalous vacuum current in three-dimensional quantum electrodynamics and the quantized Hall current. The different natures of the two currents are demonstrated, and it is shown that the effective action for the gauge field in the nonrelativistic case does not contain a genuine Chern-Simons term. This precludes any attempt to use the chiral anomaly to explain the quantized Hall effect.

Measurements of the semileptonic branching ratios of charmed $D^{+}$ and $D^0$ mesons are presented, from data collected at the $\psi \mathrm{}\left(3770\right)\mathrm{}$ in the Mark III detector at SPEAR. From a sample of events kinematically selected as charmed $D^{+}{D}^{-}$ or $D^0{\overline{D}}^0$ pairs, the branching ratios $R(D^{+}\to e^{+}+X)=(17.0\mathrm{}\pm 1.9\pm 0.7)\%$ and $R(D^0\to e^{+}+X)=(7.5\mathrm{}\pm 1.1\pm 0.4)\%$ are obtained. The ratio of these measurements can be interpreted as the ratio of $D^{+}$ and $D^0$ lifetimes $\frac{{\tau }^{+}}{{\tau }^0}={2.3}_{-0.4-0.1\mathrm{}}^{+0.5+0.1\mathrm{}}$ by neglect of the contribution of Cabibbo-suppressed decays to the total decay width.

SU(2) lattice gauge theory with two Dirac species of light, adjoint fermions included in the dynamics is simulated at finite temperatures by use of the microcanonical algorithm. The theory contains two natural mass scales, the string tension for heavy, fundamental quarks and the chiral-symmetry-breaking scale of light, adjoint quarks. The two scales are found to be distinct. This result generalizes earlier results obtained in the quenched approximation and should encourage builders of hierarchal models.

We report on a comprehensive study of supersymmetric processes which could give events similar to those observed at the CERN $\mathrm{S}\overline{p}p\mathrm{S}$ collider. The present limited data seem to suggest a gluino mass ≲ 20 GeV and a scalar-quark mass of 100- 120 GeV, although certain other supersymmetric masses are not yet excluded. With this choice of masses we also predict that other events with different characteristics should be observed. An essential ingredient of our analysis is the inclusion of events originating from a perturbatively generated gluino distribution function inside the proton.

Recently conjectured three- (and more-) body mass inequalities are investigated for the quark models of baryons in which it is assumed that baryon masses are the ground-state energies of Schrödinger-type operators with pair potentials $V$. It is proved that these inequalities hold (even with a "relativistic" form for the kinetic energy) if $V$ belongs to a certain class (which includes many potentials commonly used), but that they do not hold for all $V$ (even in the nonrelativistic case). One example of our results is $2M\left(\mathrm{cqs}\right)\mathrm{}>~M\left(\mathrm{cqq}\right)+M\left(\mathrm{css}\right)\mathrm{}$.

The data for five mass regions from $A=100-200\mathrm{}$ are plotted against the valence-nucleon product $N_p{N}_n$. They are found to display a remarkable similarity, heretofore unrecognized, which suggests a unified interpretation in terms of the strength of the proton-neutron interaction and which also leads to a better understanding of the $A=190\mathrm{}$ region.

The conditional saddle-point heights (conditional barriers) that preside over the emission of complex fragments ($Z=2-11\mathrm{}$) from compound nuclei have been obtained from the excitation functions of individual fragments in the reaction ${}_{}{}^3{}_{}{}^{}\mathrm{He}$+${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Ag}$. The magnitudes of the barriers and their dependence on mass asymmetry may be used to verify important features of the potential-energy surface including shell effects at the conditional saddle and to verify the validity of the liquid-drop model and recent refinements such as finite-range effects and surface diffuseness.

The fifteen spectral lines between 3 and 4 keV from a laser-irradiated Au plasma were identified by the relativistic Hartree-Fock-Slater method and were attributed to multiple inner-shell vacancies: one in the $3p_{\frac{1}{2}}$ or $3p_{\frac{3}{2}}$ shell and one or two more in the $M$ or $N$ shell. The splitting of two groups of lines was about 400 eV, the same as the spin-orbit splitting in the $3p$ shell.

We report on preliminary studies of the far-wing absorption of laser light into the Mg${\mathrm{H}}_2$ reactive collision complex. We have measured the far-wing absorption profile leading both to the nonreactive channel (${\mathrm{Mg}}^{*}$ formation) and into a specific vibrational-rotational level of the reactive channel [MgH ($v^{\prime \prime }=0\mathrm{}$, $J^{\prime \prime }=23\mathrm{}$) formation].

A variational scattering amplitude derived in the impact-parameter formalism is used to investigate the electronic excitation of highly charged ions by ion impact at intermediate velocities. This treatment predicts that the cross sections tend to finite limits when the charge of the projectile increases. This feature is illustrated by the good agreement between our theoretical and experimental results for the excitation of ${\mathrm{Fe}}^{24+}$ by He, N, and Ar. The excitation of H by ${\mathrm{H}}^{+}$ is studied as a check of our theory.

The spread in time intervals between the two photons produced in the process of spontaneous parametric down-conversion in a potassium dihydrogen phosphate crystal has been measured with a time resolution of the order of 100 psec. The correlation time is found to be independent of the coherence time of the pump photons or of the propagation time through the crystal, consistent with recent theoretical predictions.

Liouville's theorem and its optical counterparts are extended into the wave domain, whereby some upper bounds, representing absolute limits on the performance of passive systems, are obtained. The equality of Liouville's theorem is degraded in general to an inequality, although the limiting equality sign is sometimes realizable. The main emphasis is on optics, and the main methods those of quantum optics.

A parametric mechanism that can tailor the shape of a modulated intense relativistic electron beam was found. This mechanism is highly efficient in up-conversion of the fundamental frequency of the current modulation to the second and third harmonics. It is shown in this Letter that the parametric mechanism is the result of a nonlinear capacitance that appeared when a quasi-dc high-density electron beam traversed a high-voltage gap.

The prevalence of plasma density fluctuations in tokamaks restricts the applicability of mode-conversion theories based on quiescent plasmas. The fluctuations stimulate mode conversion between otherwise distinct fast and slow cold plasma waves near the lower-hybrid frequency. A pair of coupled differential equations representing the two waves is derived and solved under the assumption of random turbulence. This conversion may explain the observed $N_{\parallel }$ spectrum and density cutoff in tokamak lower-hybrid current-drive experiments.

We investigate the steady-state scattering function for driven diffusive systems with a single conserved density. In one dimension, density fluctuations spread as $t^{\frac{2}{3}}$, i.e., faster than the diffusive $t^{\frac{1}{2}}$, for large time $t$. The corresponding excess noise in the current-current correlation diverges as ${\omega }^{-\frac{1}{3}}$ for small frequency $\omega$. Monte Carlo simulation results for a driven hard-core lattice gas confirm these results. $d=2\mathrm{}$ is the borderline dimension with marginally nondiffusive behavior; for $d>\mathrm{}2\mathrm{}$, the spread is diffusive with anisotropic long-time-tail corrections.

Ferromagnetically interacting Ising spins are placed on a fractal network (such as a critical percolation cluster) with $T_c=0\mathrm{}$, and endowed with a single-spin-flip dynamics. At low temperatures the collective dynamics is determined by thermal activation over energy barriers. The barrier to overturning of the spins in a domain of size $L$ is proportional to $Z\ln L$, where $Z$ is a new geometrical parameter characterizing the fractal. A new "singular" dynamic scaling is found in which the effective dynamic critical exponent diverges at criticality.