A heterotic string emerges as a soliton of the heterotic five-brane. We compare its properties with the fundamental heterotic string and suggest that the two might be identified. The solution relies on the observation that the classical five-brane Lagrangian incorporates string one-loop effects.

The minimal-energy solution of the SU(2) Skyrme model with baryon number three is a soliton with tetrahedral symmetry 4¯3m. Given one assumption, I show how this symmetry ensures that the ${\mathit{J}}^{\mathrm{\pi }}$=1/$2^{+}$ isodoublet nucleus ${(}^3$He${,}^3$H) emerges as the unique ground state of this soliton solution when its isospin and rotational zero modes are quantized.

Measurements of the spin dependence of n-p elastic scatteing at ${\mathit{E}}_{\mathit{n}}$=183 MeV have been carried out with polarized neutrons and polarized protons. If charge symmetry holds, the two analyzing powers ${\mathit{A}}_{\mathit{n}}$ and ${\mathit{A}}_{\mathit{p}}$ must be equal. The measured value of ΔA==${\mathit{A}}_{\mathit{n}}$-${\mathit{A}}_{\mathit{p}}$, averaged over the angular range 82.2°≤${\mathrm{\theta }}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$≤116.1°, is (33.1±5.9±4.3)×${10}^{\mathrm{-}4}$. This result represents clear evidence of charge-symmetry violation in the strong interaction. The measurement agrees well with predictions from meson-exchange theory when these include the isospin mixing of the ${\mathrm{\rho }}^0$ and ${\mathrm{\omega }}^0$ mesons.

Partial cross sections of evaporation residues following the fusion reactions ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${+}^{68}$Zn, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{64}$Ni, and ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$${+}^{59}$Co have been measured for center-of-mass energies from 5 MeV below to 10 MeV above the Coulomb barrier. Average angular momentum l¯ has been deduced from these cross sections on the basis of statistical-model calculations. These are compared to l¯ values that can be derived from the shape of the measured excitation function of these reactions, on the basis of some simple assumptions. Good agreement is found between these two, establishing the validity of these assumptions.

Backaction-evading measurement of an optical intensity has been observed, using a three-level system in a sodium atomic beam as a nonlinear medium. The principle of this experiment is to use the cross-phase-modulation effect, which in principle allows one to read nondestructively the quantum intensity fluctuations of the ‘‘signal’’ beam when detecting the phase fluctuations of the ‘‘meter’’ beam. Using a cavity-enhancement scheme, the quantum noise measured when recombining the signal and meter photocurrents is 0.8 dB below the shot-noise level.

The cell-exit transverse profile for one-way propagation through sodium vapor forms a pattern of spots with complexity and beauty rivaling that of a kaleidoscope. These patterns are stationary in time, reproduce completely when the power or frequency is scanned, and agree well with one-way computations that show that the patterns change very little after one-fifth of the propagation distance, i.e., they exhibit the properties of bifurcations of transverse solitary waves.

A quantitative composite-particle phenomenology of the ‘‘${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{-}}$ puzzle’’ is summarized. The U+Th coincident (${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{-}}$) lines (at 809, 760, and 608 keV) arise from the decay of free composite particles and the U+Ta (${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{-}}$) lines [at 805, 748, and 620(?) keV] from decays of a particle bound to an emergent heavy ion, presumably uranium. A good semiquantitative description is obtained for the difference energies and widths observed for these six lines without any reference to the internal structure of the composite particle. This result suggests that presently available data may be insufficient to determine that structure.

Space-time analysis of the light emitted from C, ${\mathrm{C}}_2$, and ${\mathrm{C}}_3$ has been performed in a laser-evaporated carbon expansion. The measured propagation velocities and concentration evolutions display the aggregation process as a half-collision governed by momentum conservation. ${\mathrm{C}}_2$ and ${\mathrm{C}}_3$ clusters are produced with strong electron excitation, the energy excess of which is removed by photon emission instead of collisional cooling.

The $2^2$${\mathit{P}}_{1/2}$-$2^2$${\mathit{S}}_{1/2}$ (lowest-excited-state to ground-state) energy splitting in lithiumlike uranium, which has large quantum-electrodynamic corrections, has been measured using Doppler-tuned spectrometry. Our result, 280.59±0.10 eV, is more precise than current theory and is an 80-fold improvement over the previous most precise measurement of the Lamb shift in (heliumlike) uranium.

A new approach for the study of ground states of many-electron systems is developed via direct calculation of the density in density-functional theory. Not using the Kohn-Sham equations, the method divides a system into subsystems in physical space and determines the density for each subsystem. The method is demonstrated with calculations for the nitrogen molecule, which is divided into two atomic subsystems. We expect this approach to enable calcultions for large molecules beyond the reach of conventional methods.

Harmonic operation of a free-electron-laser amplifier is studied. The key issue investigated here is suppression of the fundamental. For a tapered amplifier with the right choice of parameters, it is found that the presence of the harmonic mode greatly reduces the growth rate of the fundamental. A limit on the reflection coefficient of the fundamental mode that will ensure stable operation is derived. The relative merits of tripling the frequency by operating at the third harmonic versus decreasing the wiggler period by a factor of 3 are discussed.

Using a simple mean-field model of the electron-electron interaction, we have studied the effect of space charge in a planar diode. Our results show, in particular, that the classical value for the limiting current in such a diode can be exceeded by a large factor due to the effect of tunneling. The smooth transition of the solutions from the quantum to the classical (nonquantum) regime is demonstrated.

The wavelet-transformed Navier-Stokes equations are used to define quantities such as the transfer and flux of kinetic energy through position x and scale r. Analysis of pseudospectral direct numerical simulations of turbulent flows reveals that although the mean spatial values of these quantities agree with their traditional counterparts in Fourier space, their spatial variability is very large, exhibiting non-Gaussian statistics. The local flux of energy involving scales smaller than some r also exhibits large spatial intermittency and it is negative quite often, indicative of local inverse cascades.

Nonstationary stimulated Brillouin backscattering in a large gain optical-fiber ring cavity laser exhibits superluminous Stokes pulses of quasisoliton type and partial self-induced transparency for the pump. Experimental evidences, comforted by numerical simulation of the three-wave coherent model taking the acoustic-wave dynamics into account, show that this class of long transients occurs even with a cw-coupled pump wave.

A model of the sawtooth crash is presented in which electron inertia combined with anomalous diffusion of the current replace classical resistivity in allowing magnetic reconnection to occur.

The regimes for the applicability of various theoretical models for the stability of a Z pinch under pressure balance are shown to be clearly delineated in a diagram of ln(${\mathit{I}}^4$a) vs lnN, where I, a, and N are the current, pinch radius, and line density, respectively. In particular, the most unstable regime where ideal magnetohydrodynamics applies is shown to be restricted to a small-wedge-shaped region bounded by resistive, viscous, anisotropic, and finite Larmor radius effects. Recent experimental results of anomalous stability can be interpreted in terms of resistive or large-ion Larmor-radius effects.

The linearized Vlasov-Poisson and Vlasov-Maxwell equations are shown to have a structure closely related to the evolution equation of quantum mechanics, in terms of a nonstandard Hilbert space. This Hermitian structure yields information about spectral properties, as well as a theory for dynamical invariants. We find accordingly how certain well-known features of the spectrum generalize to the nonuniform case, and we also rederive a recently found exact dynamical invariant in a very natural and simple way.

Particle-in-cell Monte Carlo simulations of rf glow discharges between parallel-plate electrodes reveal the possibility of negative period-averaged power deposited into electrons in the body of the glow. A two-fluid model of fast- and slow-electron transport demonstrates that fast electrons are compressed at the plasma-sheath boundary by the expanding sheath and are rarefied at the other (collapsing) sheath, resulting in a fast-electron density gradient through the plasma. The resulting electron acoustic waves are the key to understanding electron cooling in the body of the glow.

The singular response in the thermodynamic and geometric properties of manifolds pinned by quenched disorder to local and global perturbations is considered. The averaged displacement of a linear-extent L manifold is proportional to ${\mathit{pL}}_{\mathit{p}}^{\mathrm{\zeta }+\mathrm{\phi }}$, where p is the (small p<${\mathit{L}}_{\mathit{p}}^{\mathrm{-}1/\mathrm{\phi }}$) magnitude of the perturbation, ζ is the unperturbed roughness exponent, and ${\mathrm{\phi }}_{\mathit{p}}$ is a crossover exponent which is calculated for a variety of uniform and random perturbations. Applications to random magnets, polymers, flux lines, and magnetoresistance of localized electrons are discussed.

Hydrodynamic equations for semidilute polymer-solvent solutions are derived for both Rouse and reptation dynamics, with emphasis on the coupling between concentration fluctuations and polymer elastic stress. For the Rouse model, we project microscopic Fokker-Planck equations down to the hydrodynamic variables plus a long-lived strain variable. Also, we construct a more general two-fluid model of polymer plus solvent which shows how elastic stresses may cause diffusion currents. One important consequence of this Letter is the extension of work by Helfand and Fredrickson on Rouse solutions in weak shear to the more relevant entangled case.