The escape and synchronization of a 1-μm Brownian particle from an optical trap is presented. The probability distribution of residence times within a given well is exponential with a cutoff at short time. Temporal modulation of the well leads to synchronization.

We examine the spatiotemporal dynamics of the nonlinear three-wave interaction describing the saturation of an unstable wave by coupling to two damped waves. We observe spatiotemporal chaos involving coherent structures that are characterized by temporal and spatial scales determined by the parameters in the problem.

We describe a new method to set an upper limit of the photon mass ${\mathit{m}}_{\gamma }$ at low temperatures, based on a null test of Ampère’s law. The result of our measurements, expressed as the upper limit of the photon mass at 1.24 K, is ${\mathit{m}}_{\gamma }$≤(8.4±0.8)×${10}^{\mathrm{-}46}$ g.

We present numerical evidence that the real-time Hamiltonian dynamics of SU(2) gauge theory on a spatial lattice exhibits deterministic chaos in the semiclassical limit. We determine the largest Lyapunov exponent of the gauge field as a function of energy density, and derive a nonperturbative expression for the thermalization time.

The classical orbits of a test string in the transverse space of a singular heterotic five-brane source are classified. The orbits are found to be either circular or open, but not conic because the inverse square law is not satisfied at long range. This result differs from predictions of general relativity. The conserved total angular momentum contains an intrinsic component from the five-brane source.

By evolution of fermion mass matrices of the Fritzsch and the Georgi-Jarlskog forms from the supersymmetric grand unified scale, Dimopoulos, Hall, and Raby obtained predictions for the quark masses and mixings. Using Monte Carlo methods we test these predictions against the latest determinations of the mixings, the CP-violating parameter ${\mathrm{\epsilon }}_{\mathit{K}}$, and the ${\mathit{B}}_{\mathit{d}}^0$-B${\mathrm{¯}}_{\mathit{d}}^0$ mixing parameter ${\mathit{r}}_{\mathit{d}}$. The acceptable solutions closely specify the quark mixings, but lie at the edges of allowed regions at 90% confidence level.

We have observed over ${10}^2$ events of the type W→τν followed by τ→ hadrons, where the taus are identified by their decay into one or three charged particles. We measure the cross section times branching ratio for pp¯→W→τν and compare it to the value for W→eν to directly measure the ratio of weak coupling constants ${\mathit{g}}_{\mathrm{\tau }}$/${\mathit{g}}_{\mathit{e}}$. We find ${\mathit{g}}_{\mathrm{\tau }}$/${\mathit{g}}_{\mathit{e}}$=0.97±0.07, consistent with lepton universality.

This letter reports the full reconstruction of B mesons through the decay chain ${\mathit{B}}^{\pm }$→J/ψ ${\mathit{K}}^{\pm }$, J/ψ→${\mathrm{\mu }}^{+}$${\mathrm{\mu }}^{\mathrm{-}}$, using data obtained at the Collider Detector at Fermilab in p¯p collisions at √s =1.8 TeV. This exclusive sample, the first observed at a hadron collider, is then used to measure the B-meson cross section, from which we extract the b-quark cross section. We obtain σ=2.8±0.9 (stat) ±1.1(syst) μb for ${\mathit{B}}^{\mathrm{-}}$ mesons with ${\mathit{P}}_{\mathit{T}}$>9.0 GeV/c and rapidity ‖y‖<1.0. We obtain σ=6.1±1.9(stat) ±2.4(syst) μb, for b quarks with transverse momentum ${\mathit{P}}_{\mathit{T}}$>11.5 GeV/c and rapidity ‖y‖<1.0.

We develop a relativistic density-dependent Hartree approach for finite nuclei, where the coupling constants of the relativistic Hartree Lagrangian are made density dependent and are obtained from the relativistic Brueckner-Hartree-Fock results of nuclear matter. The calculated results on binding energies and root mean square radii of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ agree very well with experiment. The charge densities from electron scattering are also calculated and their dependence on the nucleon-nucleon interaction is discussed in relation with nuclear matter properties.

Secondary beams of radioactive heavy ions have been stored and cooled in a storage ring for the first time. Relativistic beams of bare ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ ions were produced by fragmentation of 310 MeV/nucleon ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ at the heavy-ion synchrotron at GSI. They were separated in flight with the high-resolution forward spectrometer and injected into the storage-cooler ring. The feasibilities of in-flight lifetime and direct mass measurements for radioactive beams are demonstrated.

Multistep ionization of mass-selected ${\mathrm{Na}}_{\mathit{n}}^{+}$ is found to yield ${\mathrm{Na}}_{\mathit{n}}^{\mathit{z}+}$ clusters with 2≤z≤14. The energy required for each stage of ionization is observed to vary with cluster size in a manner well described by a classical electrostatic model.

Interband excitation of single alkali-halide nanocrystals—in the form of mass-selected ${\mathit{M}}_{\mathit{n}\pm 1}$${\mathit{X}}_{\mathit{n}}^{\pm }$ beams (M=K, Cs and X=Br I)—by ultraviolet radiation leads exclusively to halogen-atom emission with very large cross section. The final state is a midgap (F-center) state. A pathway consisting of direct ejection of a photoneutralized surface atom is derived from a band picture using the computed energetics of the (3,3,3) nanocrystal ${\mathit{M}}_{14}$${\mathit{X}}_{13}^{+}$. This mechanism is contrasted with photon-stimulated desorption from crystal surfaces, and related to formation of surface defect states and metallized overlayers.

A measurement process is logically reversible if the premeasurement density operator of the measured system can be calculated from the postmeasurement density operator and the readout of the measuring apparatus. We show that the continuous-measurement version of a quantum counter, unlike the conventional photon counter, performs a logically reversible measurement. The physical origin for such a distinction is found to be sensitivity to vacuum field fluctuations.

We present an analysis of the quantum fluctuations of a three-level Λ atomic system which gives rise to lasing without inversion. We find that the intensity fluctuations in the laser output may be reduced 50% below the shot noise limit.

We have measured by laser spectroscopy the energy of interaction between a sodium atom and its images in the walls of a micron-sized cavity. This cavity-QED study is the first direct quantitative test of the Lennard-Jones van der Waals interaction as a function of controlled atom-surface separation and mean-square electric dipole moment.

We studied the effect of polyethylene-oxide (PEO, molecular weight from ${10}^5$ to 4×${10}^6$) dissolved in the micellar nematic (N) and lamellar (L) phases of the surfactant system cesium perfluoro-octanoate (CsPFO) water by microscopy and calorimetry. Replacement of water by PEO suppresses the lamellar phase above a critical concentration (${\mathit{w}}_{\mathit{c}}$) which depends on the molecular weight of the polymer by a power law. In a limited range below ${\mathit{w}}_{\mathit{c}}$ a reentrant nematic is observed. The N-L transitions become less sharp with increasing concentration. The observed effects are due to the disruption of the lamellar order by the polymer.

We present a physical interpretation of a number of exotic exponents of the two-dimensional Ising model, i.e., exponents that do have a conformal classification, but outside the unitary grid. They describe the scaling behavior of geometric properties of Ising and random clusters. For instance, the probability that two spins at a distance r lie on the perimeter of the same Ising cluster decays as ${\mathit{r}}^{\mathrm{-}5/4}$ at criticality. These results are obtained via mappings on the Coulomb gas. A part of the Coulomb gas scenario is verified by means of finite-size scaling of transfer-matrix results.

Molecular dynamic simulations for hydrogen diffusion in Pd are performed, using a potential based on the embedded-atom method. It is found that a single adiabatic Born-Oppenheimer potential energy surface cannot reproduce the wave-vector dependence of the quasielastic peak obtained in neutron scattering studies. By incorporating coupling to low-lying electron-hole-pair excitations among the conduction electrons close agreement with the experimental result is obtained. This shows that in some cases one has to go beyond the Born-Oppenheimer approximation in order to characterize correctly the diffusive motion of hydrogen in metals.

We describe molecular dynamics simulations of fluid films confined between two solid walls. The films consist of spherical molecules, or flexible linear chains with up to twenty monomers. When the wall separation is only a few molecular diameters, crystalline or glassy order is induced across the film. The onset of the glassy phase is characterized by rapidly increasing relaxation times. These manifest themselves through changes in the diffusion constant and in the response to shear. The viscosity exhibits the same power-law scaling with shear rate that was observed in recent experiments. Our study suggests that this response is a universal property of lubricants near a glass transition.

Low-energy ion scattering and surface channeling is used to study structural changes of the Pb(110) surface. There is experimental evidence for point defects (vacancies) formed at 160 K, step and/or adatom formation at 270 K, and liquidlike surface phase at 580 K. In the neutral impact collision ion scattering spectrometry mode a thermal expansion of the [11¯0] surface lattice constant of 10% at 400 K is measured.