We have measured the $K_2^{}{}_{}{}^0$ yields for electron energies of 10 and 16 GeV and at production angles of 2° and 4°, using a 40-in. hydrogen bubble chamber as a $K_2^{}{}_{}{}^0$ detector. The observed yields are compared with the predictions of a model involving the intermediate photoproduction of $\varphi \mathrm{}\left(1020\right)\mathrm{}$ mesons. In addition, we have measured the relative neutron-to-$K_2^{}{}_{}{}^0$ ratio as a function of the secondary beam momentum.

Evidence is presented to confirm the existence of an $I=\frac{5}{2}$ baryon resonance at 1640 MeV/${\mathit{c}}^2$. The resonance is observed in the reaction ${\pi }^{-}d\to \mathrm{pn}{\pi }^{-}{\pi }^{-}{\pi }^{+}$ at 2.6 GeV/${\mathit{c}}^2$ and is found to decay into $n{\pi }^{-}{\pi }^{-}$ possibly via ${\Delta }^{-}\mathrm{}\left(1236\right)\mathrm{}{\pi }^{-}$. It is shown that the observed peak cannot be due to kinematical effects such as those responsible for the $I=\frac{5}{2}$ enhancement at ≃1580 MeV/${\mathit{c}}^2$ observed earlier.

We show that there exists a strong reciprocal relationship between the algebras associated with the wave equations of Bhabha and Nambu. The representations of the two groups obtained, O(6) and O(4, 2), respectively, are the simplest algebras which can describe supermultiplets of relativistic particles.

It is shown that the Callan-Gross sum rules for electroproduction fail in perturbation theory. Nonperturbative lepton annihilation sum rules are derived. The inapplicability of perturbation theory is traced to the breakdown of the Johnson-Low-Bjorken high-energy theorem.

It is shown that all of the principal results of the Bjorken-limit technique break down in perturbation theory in the "gluon" model of strong interactions.

A vector-meson dominance model for high-energy $\mathrm{ep}$ inelastic scattering is proposed. We predict that at high values of the missing mass (>2.5 BeV) the ratio of the longitudinal to the transverse cross section is given by $\xi (\frac{q^2}{m_{\rho }^{}{}_{}{}^2}{[1-(\frac{q^2}{2m_p\nu }\left)\right]}^2$, where $\xi$ is expected to be of the order of unity. Scale invariance (in the sense of Bjorken) is satisfied at very high $q^2$. The model may adequately account for the remarkably large cross section recently observed in the deep inelastic region.

Several resonances associated with the ${\mathrm{K}}^{40}$ pure electric quadrupole interaction in KCl${\mathrm{O}}_3$ have been detected which allow the determination of the ${\mathrm{K}}^{40}$-${\mathrm{K}}^{39}$ electric quadrupole moment ratio $\frac{Q_{40}}{Q_{39}}(1.244\mathrm{}\pm 0.002)$ and the asymmetry parameter $\eta (0.621\mathrm{}\pm 0.004)$. These resonances were detected with a new steady-state double-resonance technique which has excellent stability and high sensitivity.

Measurements of grain densities of stopping ${\pi }^{+}$ and ${\pi }^{-}$ mesons in emulsion show that, in the velocity interval $0.051<\mathrm{}\beta <0.178\mathrm{}$, the energy-loss rates of ${\pi }^{+}$ mesons exceed that of the ${\pi }^{-}$ by amounts of 0 to 60 MeV/cm. The reported range differences between positive and negative particles are satisfactorily accounted for by the results of this experiment.

We have measured the impulse of a beam of charged quantized vortex rings as a function of energy and find the impulse approximately proportional to the square of the energy as theoretically predicted. This constitutes the most direct detection of vortex rings which does not rely on charged particles bound to them.

It is well known that loss-cone-type distributions which occur in mirror machines give rise to stable negative-energy waves in infinite homogeneous geometry. It is shown here that the presence of spatial inhomogeneities along the magnetic field destabilizes these waves because of the presence of dissipation associated with the flow of electrostatic waves outward to the ends of the system.

Within the framework of the Heisenberg model we have calculated the renormalization of the effective $g$ factor of magnons in cubic ferromagnets and antiferromagnets. We find a $f\left(k\right)\mathrm{}{T}^{\frac{3}{2}}$ enhancement of $g$ in ferromagnets, where $f\left(k\right)\mathrm{}\sim k^2$ for small $k$, and a $-\frac{1}{2}\frac{{\chi }_{\parallel }}{{\chi }_{\perp }}$ depression of $g$ for all antiferromagnetic magnons. We estimate that this effect will have experimental consequences of 10% or more at reasonable temperatures.

The thermal conductivity of a sample of polyethylene has been measured in the temperature range below 1°K. The results obtained are inconsistent with previous theories offered to explain thermal conduction in these materials at higher temperatures; a simple modification to the theory is suggested which is consistent with the current data.

The lattice thermal conductivity of HgSe is strongly depressed in the temperature region from 4 to 30 K. This could be accounted for satisfactorily only by a third-order (two-phonon) resonance scattering process. The relative magnitudes of the dominant Rayleigh scattering due to ionized Hg interstitials and of resonance scattering may be varied by different procedures for annealing HgSe.

The metal-semiconductor transition in ${\mathrm{V}}_2$${\mathrm{O}}_3$ is found to be suppressed above 26 kbar which corresponds to a volume compression of 0.9%. The temperature and volume dependence of the resistivity of the metallic phase is consistent with semimetallic behavior and a pressure-dependent band overlap. We propose that the metal-semiconductor transition in ${\mathrm{V}}_2$${\mathrm{O}}_3$ may be driven by the Coulomb attraction between electrons and holes and may be an example of an excitonic phase change.

We report cyclotron resonance measurements in high-purity tellurium at submillimeter wavelength confirming that the isoenergetic surfaces involved at low magnetic fields are ellipsoids grouped by pairs symmetrical with respect to the Brillouin-zone corners. We explain the violent perturbation of the Landau levels at high magnetic field by assuming the ellipsoids to coalesce into dumb-bell surfaces, as for the Shubnikov-de Haas effect.

From electron-nuclear double resonance spectra we deduce that the tetragonal EPR spectra of rare-earth ions arise from ${\mathrm{F}}^{-}$ or ${\mathrm{H}}^{-}$ ions located interstitially in the adjacent cube. The hyperfine tensor is similar in both cases. The anisotropy and the isotropic part of the hyperfine interaction must result mainly from the ${\mathrm{Ce}}^{3+}$ configurations. Simple linear combination of atomic orbitals theory would yield very different values for ${\mathrm{H}}^{-}$ and ${\mathrm{F}}^{-}$ ions. Admixture from three-electron configurations or from the odd crystal field may explain the results.

The Kallio-Kolltveit interaction is used as the effective interaction in a distorted-wave-approximation analysis of a few transitions in the reactions ${\mathrm{C}}^{12}(p,p^{\prime })$ and ${\mathrm{Ca}}^{40}(p,p^{\prime })$ at energies ranging from 25 to 55 MeV, and a comparison is made with results obtained using Yukawa interactions parametrized on the basis of low-energy nucleon-nucleon and nuclear data. It is concluded that the Kallio-Kolltveit interaction gives a good account of the basic features of the reactions, whereas the other interactions considered lead to somewhat poorer overall agreement with experiment.

Consideration is given to the relative intensities of muon-poor extensive air showers observed at mountain altitudes and at sea level. It is shown that the available results to date do not support the earlier hypothesis that primary gamma rays are responsible, and instead, a process involving charged primary cosmic rays is indicated.

Speculating on the possible existence of a strong muon-electron coupling which has escaped observation because of a multiplicative muon conservation law, we have looked for the process $e^{-}+e^{-}\to {\mu }^{-}+{\mu }^{-}$. We set an upper limit on the cross section of 0.67 × ${10}^{-32\mathrm{}}$ ${\mathrm{cm}}^2$ and conclude that such a coupling, if it exists, is no stronger than 610 times the normal vector coupling of weak interactions.

Experimental data on ${\pi }^{\pm }$ production by polarized photons are compared with a vector-dominance model prediction which is independent of a possible ambiguity regarding the frame used to evaluate the ${\rho }^0$ density matrix; a discrepancy of more than a factor of 2 is found.