Inelastic neutron-scattering experiments have been used to determine the density of states, $G\left(E\right)\mathrm{}$, of thermal excitations in epoxy resins. The results show that, over part of the range, $G\left(E\right)\mathrm{}$ increases with an energy ($E$) dependence which is higher than $E^2$. This is in accord with the predictions of the phonon-fracton model of Derrida, Orbach, and Wu. Calculations of the low-temperature specific heat using the measured density of states are in reasonable agreement with experiment, but it is shown that these calculations are very sensitive to the values of $G\left(E\right)\mathrm{}$ below $E=1\mathrm{}$ meV.

When a liquid wets a vertical wall, wetting layers form on the wall high above the liquid-vapor meniscus. These layers are stabilized against gravity by dispersion forces. For S${\mathrm{F}}_6$ in contact with fused silica, we find layers between 20 and 40 nm thick in a range of temperatures below critical. Our results support the predictions of Dzyaloshinskii, Lifshitz, and Pitaevskii, in contrast to recent experiments which are much harder to reconcile with theory.

It is demonstrated that transmission channeling may be applied to determine positions of atoms adsorbed on clean crystal surfaces under UHV conditions. For the case of deuterium on Ni(100), we conclude that the D atoms are adsorbed in fourfold hollow sites at 0.5 ± 0.1 Å above the first Ni layer and obtain a value of the rms displacement parallel to the surface in qualitative agreement with a delocalization model.

Large shifts were observed in the positions of the $3p$ energy-loss features for clear Cr(110) and Fe(110) surfaces, which were in parallel with shifts for the $M_{2,3}\mathrm{VV}$ Auger "satellite," as the primary electron energy was varied. These observations are discussed in terms of the post-collision interaction and direct recombination process following the $3p\to 3d$ transition.

Results from recent calculations of the neutron-scattering cross section for energy transfer up to 1 eV have led to a new picture of spin waves in nickel, one in which spin waves exist out to the zone boundary. Our prediction of the dispersion curve and peak widths is in general agreement with data from subsequent neutron-scattering experiments. This provides additional evidence that the "average" spin-splitting energy for nickel is in the 300- to 400-meV range.

A new recombination channel for the electron-hole plasma in silicon, at carrier densities of $n_e\gtrsim {10}^{21}$ ${\mathrm{cm}}^{-3\mathrm{}}$, is calculated. It is shown to be important in explaining the optical response of the electron-hole plasma at different probing wavelengths generated by picosecond pulses at very large fluences sufficient to melt the sample.

We argue that the sensitivity of the ear reaches a limit imposed by the uncertainty principle. This is possible only if the receptor cell holds the detector elements in a special nonequilibrium state which has the same noise characteristics as a ground ($T=0\mathrm{}$ K) state. To accomplish this "active cooling" the molecular dynamics of the system must maintain quantum mechanical coherence over the time scale of the measurement.

It is shown that a linearized time-reversal-invariant and manifestly nondissipative equation of the Schrödinger form is directly derivable from the Kolmogorov-Fokker-Planck stochastic diffusion equation in a single space dimension under certain conditions. The conditions under which this correspondence is achieved suggest the possibility of fluctuations of the space-time metric itself at short (quantum mechanical) distances as the cause of the quantum Brownian motion of microscopic particles.

A method is given for finding the shifts in position of the solitons for the case of nonzero reflection coefficient. Expressions for boost generators in terms of scattering data play a prominent role in the analysis. Phase-shift formulas which show the effect of the radiation component on the soliton motion are deduced for the nonlinear Schrödinger equation, the Korteweg-de Vries equation, and the sine-Gordon equation.

A new type of superstring theory is constructed as a chiral combination of the closed $D=26\mathrm{}$ bosonic and $D=10\mathrm{}$ fermionic strings. The theory is supersymmetric, Lorentz invariant, and free of tachyons. Consistency requires the gauge group to be $\frac{\mathrm{Spin}\mathrm{}\left(32\right)\mathrm{}}{Z_2}$ or $E_8\times E_8$.

Chiral invariance is dynamically broken for a confining Lorentz vector interaction between massless quarks. We solve the Bethe-Salpeter equation in the broken vacuum for the case of the complete light-meson spectrum, with radial and orbital excitations, up to ∼2.5 GeV. A main phenomenological conclusion is that the hyperfine $\rho -\pi$ splitting comes essentially from the Nambu-Goldstone phenomenon, independently of any spin-spin interaction. The SU(6) ⊗ O(3) classification remains, although badly broken. Degeneracy of chiral doublets is restored at high mass.

A concept of partition temperature is introduced in high-energy collisions. It is a natural mathematical consequence of the Darwin-Fowler method, and neither requires nor implies thermal equilibrium. A collision at a given incoming energy is described as an incoherent superposition of collisions with different partition temperatures. Angular distributions are then presented for $\sqrt{s}=540\mathrm{}$ GeV collisions.

The lowest-order quantum electrodynamic corrections to the energy levels of quarks bound in a spherical cavity are evaluated over a wide range of values of the quark mass. It is found that the self-energy is positive for massless quarks and decreases smoothly as the quark mass increases. The interaction energy between quarks is also calculated and found to dominate the self-energy correction. For this model, the vacuum polarization correction vanishes.

We have measured the ratio of the real to the imaginary parts of the $\overline{p}p$ forward-scattering amplitude in the incident-momentum range 360 to 650 MeV/c. These results are in good agreement with predictions of the Paris nucleon-antinucleon potential model which include spin-flip effects.

We have studied inclusive $D^{*\pm }$ production using the DELCO detector at PEP. Our technique involved kaon identification in the momentum range above 3.2 GeV/c using a threshold gas Čerenkov counter. This leads to a model-independent upper limit on $D^0-{\overline{D}}^0$ mixing of 8.1% (90% confidence level). We also have measured the charm fragmentation function, which peaks at $x\equiv \frac{P_{D^{*}}}{{(E_{\mathrm{beam}}^2-M_{D^{*}}^2)}^{\frac{1}{2}}}$ of 0.56±0.06(stat.), and the total cross section for $D^{*}$ production, $\sigma \left(D^{*\pm }\right)=0.140\mathrm{}\pm 0.021(\mathrm{stat}.\mathrm{})\pm 0.032(\mathrm{syst}.\mathrm{})$ nb ($x>\mathrm{}0.3\mathrm{}$, with radiative correction).

We study the possibility that the monojet events seen at the CERN SPS collider are produced by $Z$ decays into light scalars. These monojet events should also be seen at PETRA.

We propose a model in which the CERN monojet events are produced by the decay of the $Z$ into a new scalar and pseudoscalar. The model has many predictions which can easily distinguish it from similar competing models.

Highly polarized tagged photon were used to measure the distribution of $M1\mathrm{}$ transition strength in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ at excitations between 6.7 and 8.1 MeV. The observed $B\left(\uparrow M1\right)$ of about $19{\mu }_0^2$ can account for most of the isovector $M1\mathrm{}$ strength that is expected in the Pb nucleus. This result in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ is compared with the current experimental situation in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The discrepancy between predicted and observed $M1\mathrm{}$ strengths in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ can probably be attributed to local fragmentation of the strength into states that are too weak to have yet all been identified.

The linearized version of the extended time-dependent Hartree-Fock theory with memory effects in the collision term is used to describe the spreading width of collective states. The retention of the memory effects is shown to enforce the energy conservation between a collective state and the more complicated states responsible for its damping.

A bistable hysteresis in the cyclotron motion of a single electron has been observed which is so pronounced that it provides the best signal-to-noise ratio ever observed with a single elementary particle in a trap. The effect is due entirely to the relativistic mass increase despite very low kinetic energies between 0.016 and 10 eV. During these experiments, a single electron was trapped continuously for more than 10 months in a Penning trap.