Correlations of the coefficient of the "linear" term in the specific heat, $\gamma \mathrm{}\left(0\right)\mathrm{}$, and the discontinuity at $T_c$, $\Delta C\left(T_c\right)$, with a measured concentration of ${\mathrm{Cu}}^{2+}$ magnetic moments suggest the operation of a pairbreaking mechanism that limits the transition to the superconducting state and produces a contribution to $\gamma \mathrm{}\left(0\right)\mathrm{}$. There is no evidence for the existence of an intrinsic contribution to $\gamma \mathrm{}\left(0\right)\mathrm{}$. The value of $\Delta C\left(T_c\right)$ for a sample provides a measure of the volume fraction of superconductivity and a basis for correcting measured values of parameters to those characteristic of the fully superconducting state. Estimates of several quantities relevant to the strength of coupling are given.

We have studied the magnetotransport properties of an artificial one-dimensional crystal. The crystal consists of a sequence of fifteen quantum dots, defined in the two-dimensional electron gas of a GaAs/AlGaAs heterostructure by means of a split-gate technique. At a fixed magnetic field of 2 T, two types of oscillations with different amplitude and period are observed in the conductance as a function of gate voltage. A simple model demonstrates that the oscillations arise from the formation of a miniband structure in the periodic crystal, including energy gaps and minibands which contain fifteen discrete states.

We present results on the resistivity ρ, specific heat ${\mathit{C}}_{\mathit{p}}$, and susceptibility χ of ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_3$ near the Peierls transition ${\mathit{T}}_{\mathit{p}}$ at 180 K. Our resistivity measurements demonstrate that fluctuations intrinsic to the material persist over a temperature interval that is at least 30 K wide. Associated with the large fluctuations is en enhanced specific-heat anomaly that we analyze in terms of the short coherence lengths characteristic of many Peierls systems. We find a scaling relation between the spin susceptibility and the specific heat that covers the intrinsic fluctuation regime.

The dynamic susceptibility χ(Q,ω) of Cr+0.2 at. % V near the Néel temperature, measured by neutron scattering, is found to be clearly incommensurate, in contrast to the apparently commensurate inelastic scattering seen in pure chromium. The paramagnetic state for both compositions is well described by a single form of susceptibility previously predicted from a two-band model of the itinerant-electron magnetism of chromium alloys, which naturally combines both commensurate and incommensurate diffuse scattering.

Specular reflectivity of p-polarized light near the iron ${\mathit{L}}_{\mathrm{II}}$ and ${\mathit{L}}_{\mathrm{III}}$ absorption edges was measured from a single-crystal iron film with an external magnetic field perpendicular to the scattering plane. Large changes in reflectivity were observed upon reversal of the direction of the magnetic field. We attribute this resonant magnetization-sensitive effect to the interference between magnetic and nonmagnetic contribution to the resonant scattering. Similar effects can be expected in other ferromagnetic and ferrimagnetic systems.

We present observations of charging effects for Cooper pairs in short linear arrays of small-capacitance Josephson junctions. Current-voltage characteristics show a Coulomb gap for Cooper-pair tunneling when the charging energy exceeds the Josephson coupling energy. In a double junction a zero-voltage current is observed that is modulated by a gate voltage applied to the metal island between the junctions. For longer arrays a crossover from Coulomb blockade of Cooper-pair tunneling to a supercurrent is observed when the ratio of Josephson coupling to charging energy is increased.

We calculate, to first order in the screened electron-electron interaction, the grand potential and the equilibrium current in a mesoscopic normal-metal ring threaded by a magnetic flux. The average current in an ensemble of such rings is found to be periodic in the flux with period h/2e, and to be given at zero temperature in order of magnitude by I∼${\mathit{ev}}_{\mathit{F}}$l/${\mathit{L}}^2$, where l is the mean free path and L the circumference of the ring. Interference between time-reversed paths, as in the theory of weak localization, is the crucial ingredient. The effect decreases exponentially with temperature on a scale determined by the coherence energy ∼hD/${\mathit{L}}^2$, where D is the electronic diffusion constant. The results are in good agreement with recent measurements.

We present a new numerical method to identify the nature of a phase transition. When combined with finite-size scaling, the method can identify unambiguously a weak first-order transition even when accessible system sizes are L/ξ<0.05 as in the five-state Potts model. At a continuous transition, exponents can be determined surprisingly accurately and the computational effort required is moderate. The method is tested on the 2D Potts and 3D Ising models, but should be quite generally applicable.

We study the cosmology resulting from two coupled scalar fields, one which is either a new or chaotic-type inflaton and another which has an exponentially decaying potential. Such a potential may appear in the conformally transformed frame of generalized Einstein theories such as the Jordan-Brans-Dicke theory. The constraints necessary for successful inflation are examined. We find conventional grand unified theory models such as SU(5) are compatible with new inflation, while restrictions on the self-coupling constant are significantly loosened for chaotic inflation.

An infinitesimally thin solenoid carrying quantized magnetic flux ${\mathrm{\Phi }}_{\mathit{n}}$=nbc/e cannot be detected by point particles. However, if encircled by their world sheets, such a solenoid need not stay invisible to charged superconducting closed strings. A novel reparametrization-invariant effect, sensitive to the total (gauge-invariant) magnetic flux penetrating through the test loop, is derived. Borrowing the Kaluza-Klein language, it reflects the interplay between the σ periodicity of the world sheet and the ${\mathit{x}}^5$ periodicity of space-time.

Stacks of polycarbonate, CR-39 plastic, and BP-1 glass sheets were used to record tracks of highly ionizing particles produced in collisions of protons and antiprotons at √s =1800 GeV, with an integrated luminosity of ∼${10}^{34}$ ${\mathrm{cm}}^{\mathrm{-}2}$. No monopoles or other highly ionizing penetrating particles were found.

We suggest that dynamical breakdown of electroweak symmetry in an SU(3)×SU(2)×U(1) model of a single fermion family without fundamental scalars can reproduce the entire scalar sector of the standard model through fermion bound states and loop-induced couplings. The physical Higgs boson is essentially a tt¯ bound state. The top-quark and Higgs-boson masses are approximately 300 and 400 GeV, respectively. The strengths of the induced couplings among the scalars do not indicate a strongly interacting scalar sector.

We have analyzed the available pion-nucleon elastic scattering data with laboratory kinetic energy below 2 GeV and have extracted the charged-pion–nucleon coupling constant. The extracted value of ${\mathit{f}}^2$, using fixed-t dispersion relations, is found to be 0.0735±0.0015, a value in conflict with the result of Koch and Pietarinen, yet consistent with the value of the ${\mathrm{\pi }}^0$pp coupling determined in the recent Nijmegen analysis of pp scattering data.

The capture of many electrons by ${\mathrm{Ar}}^{17+}$ ions, at low velocity, near a metallic surface, has been studied. Multiexcited bound states with many electrons in the outermost shells (hollow atoms) have been observed. The surrounding of an ionic excited core by many outermost electrons greatly decreases the lifetimes of the states. This characteristic decrease explains the main striking features of the relaxation of the ions.

Photoelectron angular distributions for resonantly enhanced three-photon ionization (2+1) of cesium via the ns (n=8–12) states have been measured. The asymmetry parameter β is found to vary from +1.2 for the 8s state to -0.5 for the 12s state. These results provide the first clear experimental evidence for relativistic (spin-orbit) effects on the photoelectron angular distribution for an alkali-metal atom.

We report first evidence in support of chaotic stimulated Brillouin scattering under cw pump conditions involving a single Stoke and pump signal. A single-mode optical fiber is used as the nonlinear medium. The inclusion of external optical feedback modifies the form of the chaotic dynamics and results in a rich variety of classifiable precursor dynamical features.

The large-scale, long-time properties of a compressible fluid stirred by a Gaussian random force with correlation 〈${\mathit{f}}_{\mathit{i}}$${\mathit{f}}_{\mathit{j}}$〉∝${\mathit{k}}^{\mathrm{-}\mathit{y}}$ are investigated. It is shown that when ε=4+y-d>3 (d=space dimension) the effective sound velocity becomes scale dependent in the limit k→0 and the fluid obeys a universal equation of state. The effective Mach number is also scale dependent, reaching a fixed-point value ${\mathit{Ma}}^{\mathrm{*}}$(k)<1 when k→0. The predictions of the theory are compared with the results of direct numerical simulations.

A stationary, current-free, potential double layer is formed in a two-electron-population plasma due to self-consistent separation of the two electron species. The position and amplitude of the double layer are controlled by the relative densities of the two electron populations. The steady-state double layer traps the colder electrons on the high potential side, and generates a neutralized, monoenergetic ion beam on the low potential side. The field-aligned double layer is annihilated when an electron current is drawn through the plasma.

Initial two-dimensional magnetohydrodynamic computer calculations of the formation and evolution of the solid-deuterium-fiber Z pinch are reported. The computations show that the m=0 instability occurs very early in the discharge. The m=0 behavior leads to the formation of hot spots off axis and enhances the fiber ablation rate. A rapid onset of neutron production occurs when the fiber has totally ablated. The computations are in qualitative agreement with experimental observations at several laboratories and lead to a new interpretation of the experimental diagnostics.

Observations of a new type of stimulated electromagnetic emission, excited by a powerful hf electromagnetic wave in the plasma of the ionosphere, are reported. The new feature, called broad symmetrical structure, consists of two spectral maxima, symmetrically located around the pump frequency ${\mathit{f}}_0$, at offset frequencies of 15 to 30 kHz.