The initial value problem for the sine-Gordon equation is solved by the inverse-scattering method.

We place a conservative upper limit of ∼ 4.6 × ${10}^{-4\mathrm{}}$ on the fraction of antiprotons expected in the cosmic-ray flux at the top of Earth's atmosphere due to collisions of primary cosmic rays with interstellar hydrogen. The implication of this result for experiments designed to detect the existence of antimatter in the universe is discussed. We have parametrized existing data on the $\overline{p}$ inclusive cross section from threshold to intersecting-storage-ring energies to obtain the result.

We have made a systematic search for theories of interacting heavy vector mesons which have unitarily bound trees. In simple cases (four vector mesons and one scalar particle) the only unitarily bound models are spontaneously broken gauge theories. Evidently, a unitarity bound, which controls high-energy behavior, imposes internal symmetry on heavy-vector-boson interactions.

An exact bound on the ${\pi }^0\to 2\gamma$ vertex function is derived. Form it, it is possible to estimate bounds to the corrections to the vector-dominance model, the anomalous constant $S$, and the asymptotic behavior of the form factor. A theorem is derived which states that, under specific assumptions, the coefficient ($K$) of the axial current in the short-distance expansion of two electromagnetic currents is finite if ${\sigma }_{e^{+}{e}^{-}}\to \frac{1}{s}$, but vanishes if ${\sigma }_{e^{+}{e}^{-}}$ falls faster.

We suggest a lepton-hadron analogy based on the spontaneously broken SU(4) $\otimes$ SU(4) symmetry. This leads to the existence of heavy charmed particles ($1\gtrsim 5$ GeV), which may explain the rise in the total cross section of $\mathrm{pp}$ scattering at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\gtrsim 15$ GeV.

Field emission of hot electrons is observed from a laser-illuminated tungsten tip. The field dependence of the total current is accurately described by a simple theory of barrier penetration.

We find a new collective shear-wave—like mode above $T_{\lambda }$, merging with the longitudinal acoustic mode at a higher critical temperature. The speed of the new sound wave is predicted to vanish near $T_{\lambda }$ as $s\propto {(T-T_{\lambda })}^{\frac{1}{2}}$.

It is shown that the diffusion term cannot be neglected in the differential equations governing the relaxation case, even in the high-field limit. We present quantitative results of rigorous calculations including diffusion. Good agreement with experiments is obtained for reverse bias, including the typical sublinear region. In forward direction a superlinear region is found in disagreement with previous predictions of "recombinative space-charge injection."

The hydrogen-deuterium exchange reaction takes place readily on a platinum single crystal with high Miller index (997), but not detectably on a platinum single crystal of low Miller index (111). The difference in reactivity is ascribed to the large density of atomic steps present on the high-index surface that are responsible for the dissociation of the diatomic molecules.

We provide direct experimental evidence for the existence of a relaxation "bottleneck" on the lower branch of the exciton-polariton dispersion curve in CdS. The exciton life-time shows a distinct maximum of about 2.5 nsec in this energy range, as measured by time-resolved luminescence after excitation with a short, weak light pulse. There is no thermalization within the bottleneck region at 1.6 K.

Superlattice reflections below the I/II phase transition of solid heavy methane are connected with the orientational ordering that occurs. As a consequence of a temperature-dependent neutron measurement, they may be grouped into two classes, both with structure amplitudes following exponential laws but having different exponents $\beta =0.21\mathrm{}$ and ${\beta }^{\prime }=0.31\mathrm{}$. This experimental behavior is well understood on the basis of a molecular-field-type analysis, which also shows that the system is close to a hypercritical point.

We report measurements of the magnetic field positions of magnetophonon-oscillation peaks on samples of $n$-type ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te} \mathrm{}(x=0.212\mathrm{})\mathrm{}$. The band-edge effective mass $m^{*}\mathrm{}\left(0\right)=0.005\mathrm{}{m}_0$ and the effective $g$ factor $g^{*}\mathrm{}\left(0\right)=-172\mathrm{}$ are deduced from low-temperature Shubnikov-de Haas measurements. The temperature dependence of the magnetophonon peaks is interpreted using a nonparabolic band model with a temperature-dependent energy gap and a temperature-dependent band-edge effective mass. A large positive temperature coefficient $\frac{d{\epsilon }_g}{\mathrm{dT}}=+7.6\mathrm{}\times {10}^{-4\mathrm{}}$ eV/K is required to fit the experimental data.

It is demonstrated that surface states derived from the lower conduction band of $d$-band perovskites produce a square-root singularity peak in the density of surface states at energies which lie in the forbidden gap. These surface states are highly localized and have nearly pure $d$-state character. It is suggested that these surface states provide the necessary orbitals to facilitate an important class of symmetry-forbidden chemical reactions.

An experimental study of critical phenomena in thin ferroelectric films is presented which, for the first time, conclusively demonstrates that the polarization in thin films is drastically reduced as a result of depolarization effects. Other causes, like impurities, structural defects, and domain formation, which can lead to reduction of polarization, are ruled out.

Cross sections of a large variety of spallation products from V and Co do not change appreciably as the beam energy increases from 11.5 to 300 GeV. The mean ratio $\frac{{\sigma }_{300}}{{\sigma }_{29}}$ for V is 0.96±0.04; for Co, $\frac{{\sigma }_{200}}{{\sigma }_{11.5}}=0.95\mathrm{}\pm 0.06$ and $\frac{{\sigma }_{300}}{{\sigma }_{11.5}}=1.02\mathrm{}\pm 0.09$. It was assumed that the monitor cross section is constant above 10 GeV.

A semiclassical treatment of heavy-ion—induced reactions is used to analyze experimental results on the (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$) and (${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$) reactions at 80 MeV and the (${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$) reaction at 95 MeV, on a ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ target. It is shown that kinematical conditions and angular momentum coupling are sufficient to explain the strong $j$ effect and $Q$ dependence observed in the selective population of the various states.

I discuss a self-consistent, microscopic theory of nuclear rotations at high spins and review results obtained previously for the spin dependence of the moment of inertia, deformation, and energy gaps of ${}_{}{}^{160}{}_{}{}^{}\mathrm{Dy}$. Additional results given here suggest some striking discontinuities in isomer shifts, gyromagnetic ratios, and $B\left(E2\mathrm{}\right)\mathrm{}$ values at high spins. Theoretical results are consistent with the recent measurements of gyromagnetic ratios and $B\left(E2\mathrm{}\right)\mathrm{}$ values, but a greater precision is needed to test the predicted discontinuities.

Asymmetries in charged-pion photoproduction from hydrogen and deuterium have been measured with 16-GeV linearly polarized photons. Considerable energy dependence is seen in the natural-parity contribution to the $\frac{{\pi }^{-}}{{\pi }^{+}}$ ratio from deuterium, and in the unnatural-parity part of the cross section for $\gamma n\to {\pi }^{-}p$. The energy dependence of this latter cross section is consistent with the expected from a conventional pion Regge trajectory.

Momentum spectra for forward ${\Sigma }^{-}$ production on beryllium by protons of momentum $25.8 \mathrm{and} 29.4 \frac{\mathrm{GeV}}{c}$ are presented. Data for the two primary proton momenta are compared for scaling behavior in the invariant cross section. In addition, the observed single-particle momentum distributions are compared with single-particle spectra from other inclusive reactions initiated by protons.

The field-independent ($\Delta F=\pm 1$, $M_F^{}{}_{}{}^{\prime }=0\mathrm{}\to M_F=0\mathrm{}$) magnetic hyperfine transition has been observed in ground-state ${}_{}{}^{199}{}_{}{}^{}\mathrm{Hg}$ ions by optical pumping with a ${}_{}{}^{202}{}_{}{}^{}\mathrm{Hg}$ lamp. The ions were confined by a quadrupole rf electric field, imparting to them a discrete motional spectrum which leads to Doppler sidebands which can readily be resolved. The central line was observed to have a fractional linewidth not exceeding 2× ${10}^{-10\mathrm{}}$, a degree of resolution surpassed only by the Mössbauer effect. A preliminary value for the center frequency is given as 40 507 348 050 ± 50 Hz.