We have analytically evaluated, up to fourth order, all logarithmic terms in the perturbation expansion of the magnetization scrM for the Kondo model. All nonlogarithmic terms have been evaluated up to third order. When these results are compared with the claimed universal function scrM(H/${\mathit{T}}_{\mathit{H}}$) calculated with the Bethe ansatz, we find that the two cannot be made to agree whatever the form of ${\mathit{T}}_{\mathit{H}}$. We conclude that such universal functions do not exist.

The Ni 3p photoemission of ferromagnetic nickel shows a magnetic ciruclar dichroism which is much larger than expected from the value of the bulk orbital moment. We argue that this can only be explained when the orbital moment at the surface is strongly enhanced as predicted recently by band structure calculations.

The magnetic properties of Fe films epitaxially grown on Cu(100) have been correlated to their structure and morphology. Strained fcc iron films with thicknesses between 5 and 11 monolayers (ML) are ferromagnetically ordered at the surface with a perpendicular orientation of the magnetic moment, whereas the bulk of the films remains paramagnetic. The surface magnetism is related to an expanded interlayer distance at the surface. With the onset of dislocation formation at about 11 ML, the films become magnetic in the bulk and the magnetization switches to in-plane orientation.

We have observed a new cross relaxation mechanism in the presence of a pure nuclear quadrupole splitting. This process involves two simultaneous nuclear spin flips and dramatically changes the form of the magnetization recovery curves at low temperature. We present a model which combines this mechanism with spin-lattice relaxation. The addition of cross relaxation allows us to explain nonmonotonic features that were previously not understood in the recovery curves of Sc nuclei in a variety of samples.

Light scattering is used to measure the dynamics of the repetitive collapse of a sonoluminescing bubble of gas trapped in water. It is found that the surface of the bubble is collapsing with a supersonic velocity at about the time of light emission which in turn precedes the minimum bubble radius by about 0.03% of the period of the acoustic drive. These observations suggest that the shedding of an imploding shock mediates between the bubble collapse and light emission.

We consider the dynamics of a particle carrying a magnetic moment in a strong magnetic field whose direction varies slowly in space. In particular, we discuss the geometric Lorentz-type and electric-type forces that were discovered in studies of Berry’s phase. We show that the Lorentz-type force felt by the particle is caused by a small misalignment of the magnetic moment with respect to the magnetic field while the electric-type force is the time average of a strong oscillatory force induced by the precession of the magnetic moment.

We investigate the quantum mechanical bound to how precisely we can determine a phase shift given only a constraint on the mean total number of photons available. By considering how quickly one can gain information from data analysis, we derive the sensitivity achievable (in principle) for measurements involving even highly non-Gaussian noise. Using these results we calculate the sensitivity of several recent proposals for precision phase measurement, and show that no proposal to date beats the sensitivity believed achievable by squeezed state interferometry.

The discovery of the microwave background anisotropy by the Cosmic Background Explorer (COBE) satellite is in accord with the inflationary scenario. For five promising models involving a single scalar field, the coupling constants and the fluctuation spectra are calculated including a correction for gravitational radiation. The primordial density fluctuation spectrum computed from these models is not exactly scale-invariant; the spectral index is constrained to be n≳0.8 for inflation with an exponential potential (assuming that the biasing parameter for galaxies ${\mathit{b}}_{\mathrm{\rho }}$<2). The implications for biased galaxy formation scenarios are discussed.

We propose a general definition of nonequilibrium entropy of a classical stochastic field. As an example of particular interest in cosmology we apply this definition to compute the entropy of density perturbations in an inflationary Universe. On the scales of structures in the Universe, the entropy of density perturbations dominates over the statistical fluctuations of the entropy of cosmic microwave photons, indicating the relevance of the entropy of density fluctuations for structure formation.

The tau lepton electron branching fraction has been measured with the CLEO II detector at the Cornell Electron Storage Ring as ${\mathit{B}}_{\mathit{e}}$=0.1749±0.0014±0.0022, with the first error statistical and the second systematic. The measurement involves counting electron-positron annihilation events in which both taus decay to electrons, and normalizing to the number of tau-pair decays expected from the measured luminosity. Detected photons in these events constitute a definitive observation of tau decay radiation.

Results from the study of hadronic jets in hadron-hadron collisions at order ${\mathrm{\alpha }}_{\mathit{s}}^3$ in perturbation theory are presented. The focus is on various features of the internal structure of jets. The numerical results of the calculation are compared with data where possible and exhibit reasonable agreement.

Color transparency occurs if a small-sized wave packet, formed in a high momentum transfer process, escapes the nucleus before expanding. The time required for the expansion depends on the masses of the baryonic components of the wave packet. Measured proton diffractive dissociation and electron deep inelastic scattering cross sections are used to examine and severely constrain the relevant masses. These constraints allow significant color transparency effects to occur at experimentally accessible momentum transfers.

We report the first charge-state measurements of fast heavy ions passing through a plasma target. The projectiles were ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ ions at an energy of 4.8 MeV/amu and ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ ions at an energy of 5.9 MeV/amu. The target was a 20-cm-long Z pinch discharge which provided fully ionized hydrogen plasma with free electron densities up to 1.5×${10}^{19}$ ${\mathrm{cm}}^{\mathrm{-}3}$. The measured charge-state distributions are in excellent agreement with theoretical calculations. For Xe ions an increase of the ion charge state in plasma over the charge state in cold gas was observed.

We propose a high-Q Fabry-Pérot resonator with cylindrical mirrors, operating near fundamental mode and filled with an alkali vapor, as the photonic analog to the electronic quantum wire. The internal photons constitute a 1D Bose gas with pairwise interactions. We solve for the two-photon bound state which determines a resonance for the two-photon transmission function. Emphasis is placed on the experimental feasibility of observing these quasiparticles.

We demonstrate that transient four-wave mixing with time-resolved detection of the coherent nonlinear signal allows unambiguous experimental distinction between quantum beats and beats due to interfering polarizations of independent quantum-mechanical systems. The experimental demonstration is performed employing especially designed semicondutor quantum-well structures.

Millimeter-wave phase conjugation was realized under resonantly enhanced degenerate four-wave mixing in gaseous carbonyl sulfide. The nonlinear wave interaction was caused by saturation of a transition between rotational levels. For radiation with λ=1.64 mm, phase-conjugate reflectivity of about 0.4% has been observed at a gas temperature of 200 K, and under optimal pressure.

The collective free expansion of a magnetized pure electron plasma column along the confining axial magnetic field is experimentally and theoretically investigated. A new hydrodynamic theory for nonlinear plasma wave evolution in a bounded cylinder is described which predicts the experimental results. The plasma free expansion is initially characterized by a self-similar plasma flow resulting in a perturbed density and velocity with no characteristic length scale.

The surprising complexity of the reaction path of the dissociation of ${\mathrm{Sb}}_4$ and Si(001) is revealed by scanning tunneling microscopy (STM). Four distinct types of precursors are identified, which can be converted to the final state of two-dimer clusters through thermal annealing, or through a novel STM-tip-induced conversion. An effective energy barrier of 0.5±0.1 eV and an effective prefactor of ∼${10}^3$ Hz are measured for the thermal conversion of precursors to the final state. The results indicate that popular models assuming only one precursor state may fail for many semiconductor systems.

A transformation from a disordered to an ordered structure of silica has been observed at about 1 Mbar from molecular dynamics calculations. The packing of this high density phase is unique and may be important to other oxide structures. This new structure is monoclinic and is built from entirely sixfold coordinated ${\mathrm{SiO}}_6$ octahedra arranged in alternating slabs of α-${\mathrm{PbO}}_2$-type structure where the octahedra share two edges inside the slab and three edges at the boundary. In comparison with the other two structures that have been proposed within this pressure range, the stability of the monoclinic phase is more favorable than the cubic Pa3 structure but is comparable to the orthorhombic ${\mathrm{CaCl}}_2$ structure and therefore may likely coexist. The major features of the calculated diffraction pattern also fall in the same region as the ${\mathrm{CaCl}}_2$ structure.

With Monte Carlo simulation we study closed self-avoiding surfaces (SAS) of arbitrary genus on a cubic lattice. The gyration radius and entropic exponents are ν=0.506±0.005 and θ=1.50±0.06, respectively. Thus, SAS behave like lattice animals (LA) or branched polymers at criticality. This result, contradicting previous conjectures, is due to a mechanism of geometrical redundancy, which is tested by exact renormalization on a hierarchical vesicle model. By mapping SAS into restricted interacting site LA, we conjecture ${\nu }_{\mathit{F}\mathit{T}\mathit{H}\mathit{E}\mathit{T}\mathit{A}}$=1/2, ${\mathrm{\phi }}_{\mathit{F}\mathit{T}\mathit{H}\mathit{E}\mathit{T}\mathit{A}}$=1, and ${\mathrm{\theta }}_{\mathit{F}\mathit{T}\mathit{H}\mathit{E}\mathit{T}\mathit{A}}$=3/2 at the LA theta point.