A Monte Carlo calculation of the spectrum of four-dimensional U(1) lattice gauge theory has been carried out. In the scaling limit $\beta \to {\beta }_c$ massive $0^{++}$, $1^{+-}$, and $2^{++}$ states are indicated. On the critical line $\beta >{\beta }_c$ striking evidence is found for a massless photon, and no signal is found for other states.

The first complete measurement of the polarization-transfer observables in the ($p$,$p^{\prime }$) reaction at intermediate energies is reported. Data are presented for the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p,p^{\prime }){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ to the $1^{+}$, $T=0\mathrm{}$ (12.71-MeV) and $1^{+}$, $T=1\mathrm{}$ (15.11-MeV) states at 500 MeV for laboratory scattering angles of 3.5°, 5.5°, 7.5°, and 12.0°. Linear combinations of these observables are shown to exhibit a very selective dependence on the isoscalar and isovector spin-dependent components of the nucleon-nucleon interaction.

It is found that the level fluctuations of the quantum Sinai's billiard are consistent with the predictions of the Gaussian orthogonal ensemble of random matrices. This reinforces the belief that level fluctuation laws are universal.

A reflecting convex obstacle is uniquely defined by the scattering amplitude $f(k_0,{\nu }_0,n)$ known at a fixed frequency $k_0$, for a fixed direction ${\nu }_0$ of the incident wave, and for all directions $n$ of the scattered waves in a solid angle. Earlier the uniqueness theorem was proved under the assumption that $f(k,{\nu }_0,n)$ is known for $a<~k<~b$, $b>a$, and all $n$.

The authors identify symmetries of the four-dimensional Lagrangian, including the massive states, obtained via Kaluza-Klein compactification from gravity in five dimensions and ground state $M^4\times S^1$. The symmetries are described by (1) a Kac-Moody extension of the Poincaré algebra, (2) a Virasoro algebra of internal symmetries including the Salam-Strathdee SO(1,2), and (3) a mixing of (1) and (2). All symmetries are spontaneously broken save for Poincaré ⊗ U(1). The Goldstone bosons provide masses for the spin-2 tower. Higher dimensions and supergravity are discussed.

The effective gauge field action due to an odd number of fermion species in three-dimensional $\mathrm{SU}\mathrm{}\left(N\right)\mathrm{}$ gauge theories is shown to change by $\pm \pi \mathrm{}\left|n\right|\mathrm{}$ under a homotopically nontrivial gauge transformation with winding number $n$. Gauge invariance can be restored by use of Pauli-Villars regularization, which, however, introduces parity nonconservation in the form of a parity-nonconserving, topological term in the effective action.

A search for supersymmetric electron production via the reaction $e^{+}{e}^{-}\to e^{\pm }\tilde{\gamma }{\tilde{e}}^{\mp }$ followed by the decay ${\tilde{e}}^{\mp }\to e^{\mp }\tilde{\gamma }$ has been performed with the MAC detector at the electron-positron storage ring PEP. No candidates were found in a sample corresponding to an integrated luminosity of 36.4 ${\mathrm{pb}}^{-1\mathrm{}}$. For a massless $\tilde{\gamma }$ this corresponds to a lower limit on the $\tilde{e}$ mass of 22.4 GeV/${\mathit{c}}^2$ at the 95% confidence level.

The translational-energy spectroscopy is used to search for the first transitions from the $X{}_{}{}^2{}_{}{}^{}\Sigma _{\mathrm{g}}^{}{}_{}{}^{}$ ground state of ${\mathrm{H}}_2^{+}$ to bound excited electronic states. Electron impact is used to create the ${\mathrm{H}}_2^{+}$ ions from C${\mathrm{H}}_4$. It is known that electron impact on C${\mathrm{H}}_4$ creates ${\mathrm{H}}_2^{+}$ ions highly rwotationally excited. A transition is observed centered at 10.2 eV. The observed peak is assigned to the optically allowed transitions $X{}_{}{}^2{}_{}{}^{}{\Sigma }_{\mathrm{g}}_{}^{+}{}_{}{}^{}\to C{}_{}{}^2{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$.

An experiment is presented demonstrating that for both swift neutral hydrogen and proton bombardments (0.9-2.0 MeV/u) on carbon foils, the origin of cusp-shaped convoy electrons is mainly attributable to a final-state interaction between projectiles and free secondary electrons traveling with velocities around the projectile velocities near the exit surface of the target foils. The direct contribution to the cusp-shaped convoy electrons of target-electron transfer to the projectile continuum is found to be relatively unimportant.

The dependence of the optically thin third-harmonic emission on the electron density and temperature was observed to be in good agreement with theory. A one-dimensional model is used to show that the effect on calculating the central electron temperature of density profile variations is minimal, while that of temperature profile changes is small if the variations are within reasonable limits. Comparison of the temperature evolution calculated by use of the third-harmonic emission with shot-to-shot Thomson scattering shows very good agreement.

Ion heating by externally launched ion Bernstein waves is investigated in the ACT-1 hydrogen plasma. Detailed measurements of wave absorption and of the ion temperature profiles have clearly identified various heating layers near the ion-cyclotron harmonics of deuteriumlike and tritiumlike ions. The observed bulk ion heating with heating quality factor of 10 eV/W.(${10}^{10}$ ${\mathrm{cm}}^{-3\mathrm{}}$) and the power balance estimates suggest excellent overall efficiency for finite-Larmor-radius-ion-cyclotron-resonance-frequency heating.

A weak-turbulence theory of parametric instabilities in the electron-cyclotron frequency range in ELMO-bumpy-torus plasmas is developed. Parametric turbulence levels of excited modes are evaluated for principal- and second-electron-cyclotron-harmonic-resonance layers. It is shown that short-wavelength parametric turbulence may play a significant role in contemporary experiments of ELMO-bumpy-torus plasmas.

The translational diffusion coefficient $D$ of labeled poly(propylene oxide) chains in molten poly(propylene oxide) has been measured by fluorescence redistribution after pattern photobleaching both below and above the critical molecular weight for entanglement. Labeled poly(propylene oxide) was synthesized with exactly one fluorophore per molecule. The dependence of $D$ on solvent molecular weight in the entangled system is evidence that tube renewal is an important mechanism for self-diffusion in this moderate-molecular-weight polymer melt.

Sensitive ion-trapping measurements show that superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at rest contains a substantial number of quantized vortex lines, metastably pinned between the walls of the container. This remanent line density appears to be history independent, and is established upon going through the lambda point.

The authors study a symmetric two-state system with "bare" tunneling frequency ${\Delta }_0$, dimensionless Ohmic dissipation coefficient $\alpha$, and heat-bath cutoff ${\omega }_c$. Defining ${\Delta }_r\equiv {\Delta }_0{\left(\frac{{\Delta }_0}{{\omega }_c}\right)}^{\frac{\alpha }{(1-\alpha )}}$ for $\alpha <1\mathrm{}$ and ${\Delta }_r\equiv 0$ for $\alpha >1\mathrm{}$, they find to lowest order in $\frac{{\Delta }_r}{{\omega }_c}$, $\frac{\mathrm{kT}}{\hslash {\omega }_c}$ (a) for all $\alpha \mathrm{kT}\gg \hslash {\Delta }_r$, incoherent relaxation at a rate $\left(\frac{{{\Delta }_0}^2}{{\omega }_c}\right)\left(\frac{\sqrt{\pi }}{2}\right)\left[\frac{\Gamma \left(\alpha \right)}{\Gamma (\alpha +\frac{1}{2})}\right]\times {\left(\frac{\pi \mathrm{kT}}{\hslash {\omega }_c}\right)}^{2\alpha -1\mathrm{}}$; (b) for $T=0\mathrm{}$, $\frac{1}{2}<\alpha <1\mathrm{}$, incoherent relaxation at a rate $\sim {\Delta }_r$; and (c) for $T=0\mathrm{}$, $0<\mathrm{}\alpha <\frac{1}{2}$, damped oscillations with frequency $\sim {\Delta }_r$ and $Q$ factor $\frac{1}{2}cot\left[\frac{\left(\frac{\pi }{2}\right)\alpha }{(1-\alpha )}\right]$ plus a power-law background.

The first measurements of vortex diffusivity in two-dimensional superfluid helium films are reported. The diffusivity appears to be a universal function of $\frac{{\sigma }_s}{T}$, where ${\sigma }_s$ is the areal superfluid density, and is $\frac{0.4\hslash }{m}$ at the Kosterlitz-Thouless transition. In contrast with theoretical expectations, the diffusivity is a rapidly increasing function of $\frac{T}{{\sigma }_s}$ near the transition temperature.

The blue phase of cholesteryl oleate is shown to exhibit the macroscopic shear elasticity expected for a three-dimensionally ordered structure. The first measurements of blue-phase elastic constants are presented.

The authors report self-consistent linearized-augmented-plane-wave calculations of the electronic structure perburbations induced by a catalytic "poison," S, on a Rh(001) surface, focusing particularly on their distance dependence. The S-induced charge density vanishes beyond the immediately adjacent Rh atoms. However, the Fermi-level density of states, which is not screened, and which governs the ability of the surface to respond to the presence of other species, is substantially reduced by the S even at non-adjacent sites.

The dc dynamics of the sliding incommensurate chain is reduced to a purely static problem. The sliding system is described by a static hull function which becomes singular, above the critical pinning strength, as the velocity approaches zero. Both ac and dc sliding dynamics are determined numerically for the cases of weak and strong pinning and short- and long-range interactions. Excellent agreement is obtained with experiments on sliding charge-density waves near threshold, both in Nb${\mathrm{Se}}_3$ and in Ta${\mathrm{S}}_3$.

Low-temperature dispersion of the electric susceptibilities in a mixed crystal of ${\mathrm{Rb}}_{1-x}{\left(\mathrm{N}{\mathrm{H}}_4\right)}_x{\mathrm{H}}_2\mathrm{P}{\mathrm{O}}_4$ ($x=0.35\mathrm{}$) is reported. The frustrated proton ordering of this system relates it to spin-glasses. The measurements reveal a broad distribution of relaxation times. The data scale using a temperature-independent distribution of activation energies linked to the relaxation times by a Vogel-Fulcher law with a freezing temperature of 10 K.