We define a growth model analogous to the Eden model, but with two types of atoms interacting through hard-sphere potentials. In some two-dimensional cases, these models generate structures which are neither periodic nor quasiperiodic, but have a characteristic topology that distinguishes them from glasses. This topology is analogous to that of Penrose lattices. Locally, the structure is of the Hendricks-Teller type: alternation of strips of fat and skinny Penrose rhombi.

The magnetic scattering of Fe atoms in Au is measured as a function of temperature in the range between 0.08 and 4 K by means of weak localization. We find a strong temperature dependence with maximum scattering at the characteristic temperature $T_{\mathrm{K}}\approx 1$ K of this well-known Kondo system. This is a new and direct experimental approach to observation of the theoretically predicted Kondo maximum and is analogous to pair-breaking experiments in superconductivity.

Measurements of the magnetic scattering time in very thin Cu films (thickness $t\simeq 5$ nm), homogeneously doped with magnetic Cr atoms (concentration ≲100 ppm), are reported. The weak electron localization causes an anomalous magnetoresistance which is very sensitive to the spin-flip scattering of the conduction electrons. The maximum in the temperature dependence of the spin-flip scattering rate is in excellent agreement with the Suhl-Nagaoka approximation for the resonant Kondo scattering in the vicinity of the Kondo temperature $T_{\mathrm{K}}\simeq 2$ K.

A two-step resistive transition, one beginning at 240 K and the other at 90 K, has been observed in Y-Ba-Cu-O compounds. The superconductivity, possibly in granular form, at both temperatures has been verified by means of the rf-to-dc conversion associated with the ac Josephson effect.

High-resolution neutron powder diffraction experiments on the superconducting compound ${\mathrm{La}}_{1.85}$${\mathrm{Ba}}_{0.15}$Cu${\mathrm{O}}_4$ have revealed the presence of a tetragonal-to-orthorhombic phase transition at 180 K, together with subtle, anomalous structural instabilities at lower temperatures. These experiments demonstrate a correlation between the structural anomalies and changes in the electrical resistivity.

A point-contact Josephson junction between a bulk Ba-Y-Cu-O compound ($T_c\sim 90$ K) and a Nb needle has been made. The $I-V$ characteristics under microwave radiation show Shapiro steps, confirming the Josephson nature of the formed contact. Spin-singlet superconductivity in the Ba-Y-Cu-O system is implied from the voltage of the steps. The temperature dependence of the critical currents suggests that the Josephson junction if formed between Nb and another material with much higher $T_c$. Internal Josephson structure within the bulk ceramics is not found in the Ba-Y-Cu-O system.

We report novel features of potassium deposition on a Si(111)-(2×1) surface as a function of coverage. The binding is ionic even at the saturation coverage without any overlayer metallization. Up to a threshold coverage, the alkali-metal electrons are donated to the empty surface state resulting in a 1D metallic chain. Above this coverage, the conduction-band states are occupied, so that the surface electrons become itinerant leading to the metallization of the substrate and onset of enhanced conductivity.

Both anisotropic superconducting (SC) states of heavy electrons with odd-parity $p$ pairing and with even-parity $d$ pairing are shown to have an inherent instability towards the spin-density wave which generally coexists with the SC state. A model is presented which contains an on-site repulsion characteristic of heavy-fermion materials, in addition to an intersite attraction. The second transition below the SC transition observed in $\left({\mathrm{U}}_{1-x}{\mathrm{Th}}_x\right){\mathrm{Be}}_{13}$ is interpreted in terms of the spin-density-wave instability.

Surface core-level shifts for many semiconductor compounds are calculated in a tight-binding treatment, and with a local-charge-neutrality approximation. Both ideal and relaxed (110) surfaces are considered. Taking into account first-layer atomic displacements strongly modifies the values of calculated surface core-level shifts and provides a good agreement with experimental values.

A very sharp, reversible change in magnitude of the electron mobility is detected by photo-Hall effect in inhomogeneous, oxygen-doped silicon specimens. The transition temperature rises with increasing illumination flux. The light creates carriers, which neutralize charged impurities and hence reduce potential fluctuations and raise mobility.

Though having similar fractal dimensionality ($D\approx 2.5$), diffusion-limited aggregates and bondpercolation clusters are shown to have quite different second-order light scattering (SOLS) behaviors. The SOLS intensities scale as power of the fractal mass, $I^{\mathrm{}\left(2\right)\mathrm{}}\propto N^x$, with $x$ equal to ≈ 1.1 for diffusion-limited aggregates and ≈ 1.5 for bond-percolation clusters. This difference arises from the contribution of three- and four-body correlations. Thus it is suggested that SOLS can be used to reveal new structural information about fractals and to differentiate between them when they obey the same mass-size relations.

The equations of axion electrodynamics are studied. Variations in the axion field can give rise to peculiar distributions of charge and current. These effects provide a simple understanding of the fractional electric charge on dyons and of some recently discovered oddities in the electrodynamics of antiphase boundaries in PbTe. Some speculations regarding the possible occurrence of related phenomena in other solids are presented.

We compute the scalar-glueball mass m${(0\mathrm{}}^{++}$) in units of the square root of the string tension, √σ , for SU(N) gauge theories on the lattice, with N=2,3,5,6. We identify a general-scaling window in which the glueball mass is approximately independent of the lattice spacing, yielding an estimate of m${(0\mathrm{}}^{++}$) in the continuum. The estimate is corroborated by the excellent agreement between Hamiltonian and Lagrangean results for N=2,3. The continuum values of m${(0\mathrm{}}^{++}$) thus obtained for various values of N are remarkably close to each other, indicating a rapid convergence of the 1/N expansion.

A particle-physics model is presented for a large magnetic moment of the electron neutrino as required to explain the anticorrelation between the solar-neutrino flux and the sun-spot number. The model is shown to be also consistent with cosmological constraints as well as with existing laboratory experiments.

We report a search for long-lived heavy neutrinos produced by the neutral weak current in $e^{+}$$e^{\mathrm{-}}$ annihilation at 29 GeV at the SLAC storage ring PEP. Data from the Mark II detector are examined for evidence of events with one or more separated vertices in the radial range of 2 mm to 10 cm. No events were found that were consistent with the search hypothesis, ruling out heavy neutrinos with mean decay lengths of 1 to 20 cm in the mass range 1 to 13 GeV/$c^2$.

By studying lepton-kaon angular correlations in Υ(4S) decays, we have measured the branching ratios for B¯→$K^{+}$X, B¯→$K^{\mathrm{-}}$X, B¯→$K^0$/K${¯}^0$X, B¯→$l^{\mathrm{-}}$$K^{+}$X, B¯→$l^{\mathrm{-}}$$K^{\mathrm{-}}$X, and B¯→$l^{\mathrm{-}}$$K^0$/K${¯}^0$X. Their values imply that (b→c)/(b→all)=0.98±0.16±0.12.

We have observed 99 decays of the charmed strange meson, the $D_s^{+}$ (formerly called the $F^{+}$), into the φ${\pi }^{+}$ (61) and K${¯}^{\mathrm{*}0}$$K^{+}$ (38) final states in the Fermilab photoproduction experiment E-691. We determine the lifetime to be (0.${48}_{-0.05}^{+0.06\mathrm{}}$±0.02)×${10}^{-12}$ s. Using our reported measurement of the $D^0$ lifetime, we calculate the ratio τ($D_s^{+}$)/τ($D^0$)=(1.10±0.15±0.04).

Constraints on right-handed currents are set by the precise comparison of the longitudinal polarizations $P_{\mathrm{F}}$ and $P_{\mathrm{GT}}$ in Fermi and Gamow-Teller ${\beta }^{+}$ decay. Measurements with a new fourfold Bhabha polarimeter gave $P_{\mathrm{F}/P_{\mathrm{GT}=1.003\mathrm{}\pm 0.004}}$ with use of the matching isotopes ${}_{}{}^{26\mathrm{m}}{}_{}{}^{}\mathrm{Al}$ and ${}_{}{}^{30}{}_{}{}^{}\mathrm{P}$. This ratio translates directly into a bound on the product of the mixing angle ζ and mass-squared ratio δ of the left- and right-handed W bosons given by -0.49<δζ×${10}^3$<1.2 at 90% confidence.

We present a mechanism for the separation of strangeness from antistrangeness in the deconfinement transition. For a net strangeness of zero in the total system, the population of s quarks is greatly enriched in the quark-gluon plasma, while the s¯ quarks drift into the hadronic phase. This separation could result in ‘‘strangelet’’ formation, i.e., metastable blobs of strange-quark matter, which could serve as a unique signature for quark-gluon plasma formation in heavy-ion collisions.

Isotopically resolved yields of intermediate-mass fragments from ${}_{}{}^{12}{}_{}{}^{}\mathrm{-}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{induced}$ reactions on ${}_{}{}^{58}{}_{}{}^{}$,64Ni, ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Ag}$, and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ at E/A=84 MeV were measured. The systematic variation of the yield ratios with projectile and target shows that these fragments are produced by a mechanism that involves the whole target nucleus. It is demonstrated that, within a statistical interpretation, the isotope-yield ratios are a measure of the entropy and determine a relation between temperature and density at breakup.