In strong-coupling electron-lattice systems local pairs of electrons form—the so-called bipolarons. They behave like a Bose liquid on a lattice and have very small bandwidth $b$. We show that the specific heat for those bosons in the normal phase is extremely similar to that obtained for electrons in equivalently narrow bands: a behavior linear in $T$ for low temperature ($T<<t$) and a $T^{-2\mathrm{}}$ law for high temperature ($T>~t$). In contrast, the magnetic susceptibility for triplet bosons differs qualitatively from that of electrons in the low-temperature regime. We discuss those results in view of a possible application to compounds exhibiting heavy-mass carriers.

Nondestructive magnetic depth profiling with spin polarization of secondary electrons reveals a particular magnetic state within the outermost 5 Å of the Fe(100) surface. This state is the first step in reversed-domain nucleation and is best described as a very thin 90° [100] wall, which is forbidden in bulk Fe.

High-precision measurements of the electrical resistivities of $K\mathrm{Rb}$, $K\mathrm{Na}$, and $\mathrm{Li}\mathrm{Mg}$ alloys reveal large anomalous departures from the expected $T^2$ dependence below Å 0.5 K. The dependences of the anomaly in $K\mathrm{Rb}$ upon temperature, residual resistivity, and magnetic field have been studied and, taken together, appear to rule out localization, electron-electron interaction, or Kondo effects as explanations for the anomaly. Two-level-system and charge-density-wave explanations are also considered.

The dielectric theory of Phillips and Van Vechten defines crystalline ionicity in terms of optical properties and predicts first-order structural phase transitions. Their approach, while very successful, is, nonetheless, empirical and has yet to be justified via an ab initio quantum mechanical approach. We present such an approach for examining the relationship between spectroscopic crystal ionicity and spatial structure. We demonstrate that the structural predictions based on ionicity scales derived from the dielectric theory are consistent with a microscopic point of view.

An experiment is described in which electrons are ejected from a metallic surface upon bombardment by molecular clusters formed in a supersonic jet expansion.

Impurity cyclotron resonance (ICR) has been observed in $n-{\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te}$. This experiment provides conclusive evidence for donor-bound electrons in this semiconductor. The separation between the ICR and the free-carrier resonance is in satisfactory agreement with theoretical predictions for hydrogenic donors in a strong magnetic field. Saturation of the ICR absorption was used to determine the electron lifetimes of Å ${10}^{-6\mathrm{}}$ sec in the lowest Landau level.

We report new Hall measurements on ${\mathrm{}\left(\mathrm{TMTSF}\right)\mathrm{}}_2$P${\mathrm{F}}_6$ under pressure. Our data, and a simple model, directly link the novel magnetic-field-induced state first seen in the Bechgaard salts to a well-characterized ambient-pressure spin-density-wave state. Comparison of the data for different salts suggests that (1) incommensurability associated with a two-dimensional lattice in a magnetic field splits the Landau levels into Landau subbands, and (2) coupling to soft modes changes the field-induced spin-density-wave transitions from second order to first order.

A generalized average inverse participation ratio, for the one-electron wave functions of a dilute tight-binding model on a $d$ dimensional hypercubic lattice, is studied at finite magnetic fields. Extended wave functions appear above a quantum threshold bond concentration, $p_q$. This threshold decreases at small magnetic fields, and shows a periodic dependence on the magnetic flux through a basic plaquette, with period ${\phi }_0=\hslash \frac{c}{e}$. Extended states appear and disappear periodically even at $d=2\mathrm{}$.

Barely insulating and barely metallic Si:As samples have been studied in the temperature range 4.2 K to 50 mK. Metallic samples show a new high-field magnetoresistance behavior explainable in terms of magnetic tuning of the critical density $N_c$. Insulating samples at fixed fields show Mott variable-range-hopping behavior and the increase of characteristic temperature $T_0\mathrm{}(N,H)\mathrm{}$ with $H$ results primarily from magnetic tuning of the localization-length exponent $\nu$. Magnetocapacitance results depend on field-induced changes in both $N_c$ and $\nu$.

We present SQUID measurements of the nonlinear susceptibility ${\chi }_{\mathrm{nl}}$ of "pure" CuMn and CuMn doped with gold impurities with concentrations $C_{\mathrm{Au}}$ of 1, 2, and 3 at.%. Gold impurities suppress the magnitude of ${\chi }_{\mathrm{nl}}$. Ordinary one-parameter scaling with respect to field and temperature is obeyed by ${\chi }_{\mathrm{nl}}$ of the pure CuMn. However, strong deviations from this scaling behavior are observed in the gold-doped samples in the vicinity of the freezing temperature and in low fields, $H<\mathrm{}{H}^{*}$ where $H^{*}$ increases with $c$. This is interpreted as the onset of an anisotropy-induced crossover from a Heisenberg to an Ising spin-glass critical behavior.

There appears a possibility that the correct cosmological baryon asymmetry is generated in the late baryogenesis scenario combined with electroweak baryon-number nonconservation at finite temperatures. In this scenario we expect almost isothermal baryon-density perturbations, which can be large enough to make the nonlinearities needed for the formation of globular clusters.

A total of 1.9×${10}^6$ good-quality high-energy muon events were analyzed from the data of the underground Kamioka nucleon-decay experiment. No definite sign of excess flux was observed in the direction of Cygnus X-3 and in its phase interval of 0.7 to 0.8. The 90%-C.L. (confidence level) upper limit for the excess flux is 2.2×${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ for rock overburden greater than 2400 m of water equivalent.

It is shown that a trapped surface can be extended, in a locally area-preserving fashion, to a three-cylinder that is everywhere spacelike, provided it encounters no singularities in its development. Thus the interior of a regular, area-preserving, initially trapped surface is permanently sealed off from causal influence on the exterior world.

Evidence for the Aharonov-Bohm effect was obtained with magnetic fields shielded from the electron wave. A toroidal ferromagnet was covered with a superconductor layer to confine the field, and further with a copper layer for complete shielding from the electron wave. The expected relative phase shift was detected with electron holography between two electron beams, one passing through the hole of the toroid, and the other passing outside. The experiment gave direct evidence for flux quantization also.

We present the results of an experimental investigation of the production in the nuclear Coulomb field of low-invariant-mass pions pairs by the reaction ${\pi }^{\mathrm{-}}$Z→${\pi }^{\mathrm{-}}$${\pi }^0$Z at 40 GeV. We have obtained for the first time the experimental value of the γ→3π coupling constant $F^{3\pi }$(0)=13.0±0.9±1.3 ${\mathrm{GeV}}^{\mathrm{-}3}$, where the first (second) error is statistical (systematic). This result is in agreement with calculations based on the theory of chiral anomalies.

We have measured the inclusive branching ratio for B→φX to be 0.023±0.006±0.005. The momentum distribution of the φ mesons is compared with that expected from the cascade decays B→F→φ and B→D→φ. .AE

We have analyzed available data on magnetic dipole and electric quadrupole amplitudes for the photoproduction of pions around the delta region, in the framework of a phenomenological γNΔ interaction and background. The unitarity constraint via Watson’s theorem limits severely the range of allowed gauge couplings in the γNΔ vertex. We obtain (-1.5±0.2)% as the ratio of the electric quadrupole to magnetic dipole resonant amplitudes, a value of the same order of magnitude as predicted in the skyrmion model of baryons. This ratio suggests a deformed structure of the nucleon and the delta isobar.

In a study of large-$p_T$ jet production in 200-GeV/c πp and pp collisions, we find evidence for pion-induced dijet events with little or no forward energy flow. The rate and characteristics of these events are compatible with the predictions of Berger and Brodsky for higher-twist processes. No corresponding signal is seen in pp collisions.

We have measured the branching fraction of ${\tau }^{\mathrm{-}}$→${\rho }^{\mathrm{-}}$${\nu }_{\tau }$ to be (22.3±0.6±1.4)% and the branching fraction of ${\tau }^{\mathrm{-}}$→$K^{\mathrm{*}\mathrm{-}}$${\nu }_{\tau }$ to be (1.3±0.3±0.3)%. These values are consistent with the expectations for conventional decays of the τ.

We use the microcanonical demon method to determine nonpertubatively the renormalization of the gauge coupling constant as well as the effective magnetic field due to fermions within the framework of pseudofermionic simulations of finite-temperature QCD.