Two experiments are reported in which a search was made for the scalar boson predicted to be produced in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(6.05 MeV) to ground state and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(20.2 MeV) to ground state $0^{+}$ to $0^{+}$ transitions with subsequent in-flight decay into electron-positron pairs. Taken together, our results show that the light scalar boson proposed by Sundaresan and Watson to account for certain muonic x-ray energy discrepancies cannot have a mass in the range $1.030<~m<~18.2$ MeV.

For $\overline{p}d$ annihilations at rest, charge independence and energy conservation imply that the average energy going to charged pions is $〈E_{\pm }〉=1241\mathrm{}\pm 2$ MeV per annihilation. Experimentally this number is found to be 1169 ± 10 MeV after corrections for events with invisible $K^0{\overline{K}}^0$. This discrepancy of 72 ± 10 MeV cannot be accounted for by the known $\eta$ and $\omega$ production which is estimated to contribute ∼ 14 ± 3 MeV.

The charge-independence-violating effects observed in the previous paper are caused by the production of 0.73 ± 0.08 $\gamma$ per annihilation above what is expected, 3.04 ± 0.02, from charge independence. The $\gamma$-energy spectrum extends over the $\gamma$ spectrum generated from ${\pi }^0$. The spectra associated with specific topologies show peaks which are indicative of electromagnetic transitions between $\overline{p}N$ bound states or states of the cosmion ($C$).

In the colored-quark model, if the three vector gluons that correspond to an SU(2) subgroup of SU(3) are heavier than the other gluons, a quark-diquark structure for baryons results. Furthermore, the predicted baryon SU(6) representations are the 56 for even parity and the 70 for odd parity, in agreement with recent experimental indications.

The ultraviolet freedom of non-Abelian gauge theories is used to suggest the presence of a new symmetry of the exact theory which is not present in finite orders of perturbation theory. The infrared behavior of these theories is determined as a consequence of this symmetry.

We extend the technique of quantum-beat spectroscopy to the infrared region by utilizing the strong, directional absorption and emission which occurs in photon echoes and optical nutation. Using a vibrational transition of N${\mathrm{H}}_2$D, we have made the first observations of infrared quantum beats in these phenomena. The hyperfine splitting which produces the quantum beats has not been observed in Lamb-dip spectroscopy but is clearly resolved in these time domain studies.

We report the first experimental and theoretical investigation of the coupling of second-harmonic generation of light to surface plasmons in thin silver films. A model of second-harmonic generation due to polarization sources at the silver-air interface correctly predicts the observed harmonic enhancement of one and a half orders of magnitude because of excitation of the surface plasmon.

The interaction between charged particles and sharply localized fields is investigated. The random particle scattering is described by a Fokker-Planck equation whose time-dependent solution exhibits the formation of a highly populated superthermal tail.

The rf preferential plugging of multi-ion species plasma is studied experimentally in a magnetic cusp: Desired ion species can be plugged and the others escape from the container. The conditions necessary to realize an impurity-free cusp reactor using this concept are discussed. It is shown that impurities, specifically krypton and argon, can be preferentially reduced in the reactor.

A renormalization-group technique is used to study the critical behavior of spin models in which each interaction has a small independent random width about its average value. The cluster approximation of Niemeyer and Van Leeuwen indicates that the two-dimensional Ising model has the same critical behavior as the homogeneous system. The $\epsilon$ expansion for $n$-component continuous spins shows that this behavior holds to first order in $\epsilon$ for $n>\mathrm{}4\mathrm{}$. For $n<\mathrm{}4\mathrm{}$, there is a new stable fixed point with $2\nu =1+\left[\frac{3n}{16(n-1\mathrm{})\mathrm{}}\right]\epsilon$.

A new approach to strongly coupled plasmas is proposed by a scheme linking the linear and quadratic polarizabilities through a self-consistency requirement. The ingredients of the theory are (a) replacement of the nonequilibrium two-particle correlation function by its velocity average; (b) the connection between the nonequilibrium two-point function and the equilibrium three-point function; (c) the link provided by the nonlinear fluctuation-dissipation theorem between the quadratic polarizability and the three-point function.

The Faraday rotation of small polarons is investigated. For three-site hopping the rotation angle has maxima located symmetrically about the frequency at which there is a maximum in the optical absorption. For four-site hopping, the rotation angle is found to exhibit an anomalous change in sign. Experimentally determined parameters for rutile (Ti${\mathrm{O}}_2$) suggest that the anomalous four-site effect is observable.

It is shown that a mode of dislocation motion exists in the modified Frenkel-Kontorova model in which the dislocation moves at a high constant speed without exciting any lattice waves and with no applied stress required to maintain the motion. The Peierls stress, ${\sigma }_{\mathrm{p}}$, for the model parameters employed has the value ${\sigma }_{\mathrm{p}}=0.0506\mathrm{}\mu$, with $\mu$ the shear modulus, so that this result provides an example of a dislocation subject to a periodic Peierls potential in its steady motion, without this fact giving rise to radiation losses.

The lattice contribution to the diamagnetic susceptibility, ${\chi }_L$, is written as a sum of three terms, a core term ${\chi }_c$, a Langevin-like valence-electron contribution ${\chi }_v$, and a Van Vleck paramagnetic term ${\chi }_p$ using a one-oxcillator model. Measurements of ${\chi }_L$ and $\frac{d{\chi }_L}{\mathrm{dT}}$ for diamond, Si, Ge, GaAs, and GaP are presented. The model allows a separate determination of each of the three terms and relates these terms to the symmetry and extent of the valence-bond charge distribution.

The shape of the $K$ absorption edge of Li has been measured at 293, 373, 443, and ∼480 K (liquid) by photoyield methods. Unpublished transmission data on the shape of the edge at and below room temperature have been reanalyzed. There is a marked increase of the width of the edge with increasing temperature above 293 K, indicating that the lattice plays a major role in the broadening of the edge.

The polarized reflectance of single crystals of tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) at 300 K is reported over the frequency range 300 to 4000 ${\mathrm{cm}}^{-1\mathrm{}}$, with unpolarized data extending to 50 ${\mathrm{cm}}^{-1\mathrm{}}$. A Kramers-Kronig analysis is used to obtain the frequency-dependent conductivity ${\sigma }_1\left(\omega \right)$ and dielectric function, ${\epsilon }_1\left(\omega \right)$, for both $a$ and $b$ crystallographic axes. The results establish the existence of the energy gap and provide a quantitative measurement of the oscillator strength and relaxation time of the collective mode.

I have measured the low-temperature electrical resistivity $\rho \mathrm{}\left(T\right)\mathrm{}$ for a series of $\mathrm{Pd}\mathrm{Fe}$ alloys with and without hydrogenation. For Pd + 0.2 at.% Fe, the sharp decrease in $\rho \mathrm{}\left(T\right)\mathrm{}$ at the Curie temperature gives way to a broad Kondo-like minimum. With increasing Fe concentration, the giant-moment ferromagnetism is severely hindered by hydrogen charging, and $\rho \mathrm{}\left(T\right)\mathrm{}$ shows the characteristics of an interacting Kondo system or a "spin glass."

Data are presented on ${\mathrm{In}}_{1-x}{\mathrm{Ga}}_x{\mathrm{P}}_{1-z}{\mathrm{As}}_z-\mathrm{Ga}{\mathrm{As}}_{1-y}{\mathrm{P}}_y:\mathrm{N}$ heterojunctions showing that for the N trap located (∼ 5 meV) in the $\Gamma$ conduction band ($E_{\mathrm{N}}>E_{\Gamma }$) of $\mathrm{Ga}{\mathrm{As}}_{1-y}{\mathrm{P}}_y:\mathrm{N}$, band-to-band laser operation tends to be quenched locally. The index dispersion quantity ($n-\lambda \frac{\mathrm{dn}}{d\lambda }$) exhibits a large local increase due to the $k\ne 0$ components the trap introduces in the recombination process. These results are interpreted as the resonant-antiresonant behavior of the trap state interacting with the conduction-band density of states.

Particle emission yields from cold-rolled and annealed Fe, Nb, and Au surfaces under MeV proton bombardment are reported. 16-MeV protons are used to simulate the surface sputtering by 14-MeV neutrons which is of interest for nuclear fusion. Sputtering yields of less than 2 × ${10}^{-4\mathrm{}}$ are reported. "Chunk emission" is not observed.

By consideration of infinite, isolated spirals of Se atoms, it is shown that the differences of the density of valence states of amorphous and trigonal Se determined from photoemission experiments can be explained by a possible change in the average dihedral angle from 102° in the trigonal form to ∼ 80° in the amorphous form. Previous interpretations based upon the increased interchain separation of the amorphous form are in contradiction with the present results.