Covariant actions are proposed for classical superstrings immersed in eleven space-time dimensions by construction of simple Chern-Simons terms. Local world-sheet variables are used which are space-time vectors, Majorana spinors, and antisymmetric tensors.

Spontaneous R-parity breaking in supergravity solves the solar neutrino problem through matter-enhanced neutrino oscillations. The model may be tested in collider experiments and through ‘‘dynamical’’ effects associated with the existence of a weakly interacting majoron. Apart from astrophysical effects, majoron emission can produce observable changes in μ and τ decay spectra for parameter values that substantially reduce the solar neutrino flux. A signature of the model is the possible observation of the decay μ→e+majoron.

In the minimal sypersymmetric model, we show that the branching ratio for a heavy gluino (${\mathrm{M}}_{\mathrm{g}\mathrm{̃}}$≳600 GeV) to decay directly into the lightest supersymmetric particle is less than 14%, independent of nearly all parameter assumptions. Thus, the traditional jets+${\mathrm{E}}_{\mathrm{T}}^{\mathrm{miss}}$ signature is substantially reduced. We describe the results of a comprehensive survey of search strategies as a function of the supersymmetric parameter space, and identify those which are most promising. We consider a range of gluino masses appropriate to both existing and future colliders.

Central collisions of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nuclei with the ${}_{}{}^{107}{}_{}{}^{}\mathrm{Ag}$ and ${}_{}{}^{80}{}_{}{}^{}\mathrm{Br}$ nuclei in nuclear emulsion at 14.6, 60, and 200 GeV/nucleon are compared with proton-emulsion data at equivalent energies. The multiplicities of produced charged secondaries are consistent with the predictions of superposition models. At 200 GeV/nucleon the central particle pseudorapidity density is 58±2 for those events with multiplicities exceeding 200 particles.

Giant resonances were observed in (${\pi }^{+}$,${\pi }^{\mathrm{-}}$) double charge exchange (at $T_{\pi }$=292 MeV) on ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{80}{}_{}{}^{}\mathrm{Se}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at excitation energies of 28.5, 34.6, and 43.6 MeV, respectively. An angular distribution for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ was measured and observed to have a dipole shape. The variation of excitation energy above the double isobaric analog state is consistent with an $A^{\mathrm{-}1/3}$ dependence, as expected for giant dipole resonances built on the isobaric analog states. The ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ angular distribution agrees well with a coupled-channels impulse-approximation calculation in which sequential single charge exchange through the isobaric analog to the giant dipole resonance is evaluated.

Well-developed sine-wave self-pulsing has been observed in the beam transmitted by a passive cavity containing a molecular gas, subjected to a cw incident beam. The free spectral range of cavity is comparable to the Rabi frequency inside the cavity and much larger than the relaxation rate. The self-pulsing is attributed to the multimode instability predicted by Bonifacio and Lugiato in 1978 but not yet observed.

We describe the operation of a hydromechanical resonator immersed in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathit{B}$ superfluids and opened on the main bath by two holes, a micro-orifice acting as a weak link and a long parallel channel. Transitions between adjacent quantum states differing by one hydrodynamic circulation quantum can be induced coherently, yielding a succession of steps arranged in a staircase pattern. In ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at about 0.8 mK and 0 bar, a nearly ideal, nondissipative hydrodynamic Josephson effect can be observed.

Absoulute specific-heat measurements are presented for the solid phase and upper limit of 0.2${\mathrm{k}}_{\mathrm{B}}$ per particle is established for the change in entropy on melting. The results support the dislocation-pair–unbinding model of Kosterlitz and Thouless.

A theory for the growth of columnar microstructures in thin films is presented. The zone-I to zone-II transition temperature is predicted. The surface morphology and the columnar grain structure are obtained both analytically and numerically, and the scaling behavior of the columnar grain size with film thickness is derived. Monte Carlo simulations are used to follow the evolution of the three-dimensional zone-II microsctuctures and to account for the formation of film texture. These results agree with experimental observations.

Nuclear magnetic susceptibility measurements of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in dilute ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixture films are presented. At low ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ coverages ($d_3<0.1\mathrm{}$ layer), the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ behaves approximately as a 2D ideal Fermi gas. For larger submonolayer ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ coverages, the low-temperature susceptibility is enhanced, increasing with increasing amounts of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, contrary to the 2D ideal Fermi-gas model. No evidence for a phase transition in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is seen.

Surface melting in Ne films evolves with thickness from logarithmic to power-law temperature dependence. The thin-film behavior appears to be due to the expected exponential decay of solid order. The variation with thickness of the melting entropy is examined to determine the profile of the crystal-melt interface. The interface width is approximately 6 layers in Ne and 4 in Ar.

Detailed photoemission studies of the Tm/GaAs(110) interface give clear evidence for an abrupt change in Fermi-level position at a relatively high Tm coverage (≃2.6 Å) by 0.22 eV towards the value expected from current-voltage measurements. This observation together with the strongly increasing density of states at the Fermi level around this coverage indicates that the Schottky barrier is not established until the overlayer assumes metallic character. The results are interpreted within the concept of metal-induced gap states defining the final Fermi-level position in Schottky barriers.

Ag is deposited on room-temperature and low-temperature GaAs(110). Correlation is found between the appearance of metallicity in the Ag layer, as inferred from the width of the Ag-4d band, and the pinning of the Fermi level at the GaAs surface. These results suggest the importance of metal-induced gap states at high coverage (>2 Å) in the formation of the Schottky barrier.

We study the 1D quasiperiodic quantum Ising model in a transverse field, which exhibits long-range order above a critical coupling and describes the phase diagram of the 2D classical Ising-model quasiperiodic in one direction. We numerically determine the correlation length, magnetization, and energy spectrum of this system. The site dependency of the magnetization is described by a new order parameter, the width of the magnetization. The scalings δ and f(α) associated with the Cantor spectrum are found to exhibit special features at the onset of long-range order.

Optical and electronic properties of ${\mathrm{In}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As strained-layer superlattices grown on InP have been investigated over the entire range of indium compositions, 0<x<1. We demonstrate a type-I to type-II superlattice transition at x≲0.20. Below this critical concentration electrons become confined to the InP layer. Excellent agreement is obtained with a band-structure calculation based on empirical relative valence-band energies and deformation-potential theory. This agreement suggessts that the effect of strain on these relative energies can be neglected.

We report the temperature dependence of the electrical resistivity of carbon at atmospheric pressure and temperatures up to and above the melting point at 4450±100 K. Vapor-grown graphite fibers of different crystalline perfection were heated with 28-μsec electrical pulses. We also measure the transient reflectivity of graphite irradiated with picosecond laser pulses and find evidence for nonequilibrium heating. We conclude that liquid carbon is metallic with a nearly temperature-independent electrical resistivity of 30±8 μΩ⋅dm.

The optical-absorption spectrum of an excess electron solvated in a molecular sample of liquid water at 300 K has been calculated with use of solvent configurations generated via path-integral simulation and subsequent solution of the excess-electronic eigenvalue problem. Electronic transitions from an s-like ground state to three bound-localized, p-like excited states dominate the broad asymmetric spectrum with excitations into an apparent continuum following at higher energy. Asymmetric distortions and radial fluctuations of the solvent cavities contribute comparably to the spectral broadening.

By combining several spectroscopic techniques, we have observed a new type of bistable center in electron-irradiated silicon and have identified it as an interstitial-carbon–substitutional-carbon pair. The positive and negative charge states of the defect share a common stable configuration which differs from that for the neutral state by a simple molecular bond rearrangement. Detailed structural models and configurational-coordinate energy surfaces are presented for each of the three charge states.

We report the first direct measurement of the polarization divergence associated with charge-density-wave depinning in ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_3$ at low temperatures. The field-dependent remanent polarization diverges as P(E)=${\mathrm{P}}_0$(1-E/${\mathrm{E}}_{\mathrm{T}}$${)}^{\mathrm{-}\gamma }$ with ${\mathrm{E}}_{\mathrm{T}}$ the threshold field and the ‘‘critical exponent’’ γ<1. We discuss the novel effects associated with the polarization divergence and the inherent difficulties of the analysis.

We extend the inverse problem for multifractals to include the generalized logarithmic dimensions and the generalized metadimensions. These dimensions are shown to contribute characteristic $n$-dependent corrections to the scaling function, where $n$ is the stage of scaling refinement. We establish a connection between these corrections and the type of dimensions and demonstrate the utility of such a connection in the specific case of one-dimensional maps.