The giant susceptibilities and their suppression by small magnetic fields observed for dilute La-rare-earth alloys are explained quantitatively by assuming clustering of localized spins.

We calculate qualitatively the cohesive energy and density of metals which theoretically should condense in high-pressure systems containing high concentrations of muons and various isotopes of hydrogen. The resulting metallic forms are found to be thermally superstable suggesting that they may perhaps exist briefly and in small quantities in some stellar environments.

Given a conserved tensor field $f_{\mu \nu }\mathrm{}\left(x\right)\mathrm{}$, we formulate a simple set of conditions under which $f_{\mu \nu }$ can be used in place of the symmetric stress-energy tensor ${\theta }_{\mu \nu }$ to construct the generators of the Poincaré group. We make a comparison with the Dirac-Schwinger condition, and we discuss the relevance of the result to Sugawara's theory of currents.

Loss of mass energy from the galaxy, whether by gravitational radiation or otherwise, should cause the galaxy to expand. Observations of stellar motions near the sun imply that the rate of radiation averaged over the last ∼${10}^8$ yr must be less than ${200M}_{\odot }$ ${\mathrm{yr}}^{-1\mathrm{}}$. Studies based on the 21-cm line have already yielded some evidence for galactic expansion, which could be a consequence of mass loss.

Evidence is presented for the existence of an $N^{*}\mathrm{}\left(1710\right)\mathrm{}$ ($M=1712\mathrm{}\pm 6$ MeV and $\Gamma =70\mathrm{}\pm 15$ MeV) produced in the reaction $K^{-}p\to K^{-}p{\pi }^{+}{\pi }^{-}$ at incident momenta of 3.9, 4.6, and 7.3 GeV/c. It decays mainly into $p{\pi }^{+}{\pi }^{-}$ and not through the ${\Delta }^{++}{\pi }^{-}$ intermediate state, with some indication for a $\Lambda K^{+}$ decay mode. Also observed in the $p{\pi }^{+}{\pi }^{-}$ invariant mass spectrum is the $N^{*}\mathrm{}\left(1470\right)\mathrm{}$.

Data on photoproduction of muon pairs are reported and compared with quantum electrodynamics. A new average value of $B_{\rho }=\frac{({\rho }^0\to {\mu }^{+}+{\mu }^{-})}{({\rho }^0\to \mathrm{all})}=(8.2\mathrm{}\pm 1.6)\times {10}^{-5\mathrm{}}$ is obtained. Comparison with $B_{\rho }$ for electron pairs provides a valid experimental confirmation, to "distances" of 1.6×${10}^{-14\mathrm{}}$ cm, of ($e, \mu$) universality for vertices involving timelike photons. We interpret the paradoxical agreement of values of $B_{\rho }$ for photoproduction experiments with those for colliding beams in terms of the $\rho$, $\omega$ phase.

In the dual resonance model, introducing a generalized gauge-transformation operator which leaves the vertex functions invariant, we present a general treatment of linear dependences among the vertex functions. We also prove that the two propagators recently discussed in connection with the twisting operator are equal up to our gauge transformation.

The vector-dominance model for inelastic $e-p$ scattering is re-examined using an invariant procedure which also satisfies gauge invariance and all kinematic analyticity requirements. By explicitly exhibiting the inherent arbitrariness in the choice of extrapolation functions, it is shown that the previous prediction of large $\frac{{\sigma }_S}{{\sigma }_T}$ at large $q^2$ (which disagrees with recent data) is not a general feature of this model. Alternative examples which also satisfy both of Bjorken's scaling conditions are given.

Measurements of spin-lattice relaxation in nematic and smectic liquid crystals are contrasted to recent theoretical predictions for $T_1$ in these phases.

We use the density dependence of the NMR frequency of xenon nuclei to investigate the xenon liquid-vapor coexistence curve near $T_c$. A pure power law fails to describe our precise values of ${\rho }_L-{\rho }_V$ for ${10}^{-5\mathrm{}}<\epsilon <{10}^{-2\mathrm{}}$. We have determined the temperature dependence of ${\beta }^{*}$ in this range; the critical exponent $\beta$ of the asymptotic power-law behavior must be obtained by extrapolation of ${\beta }^{*}$ to $T=T_c$.

Efficient modulation of atomic-line-emission intensity by high-frequency plasma oscillations (∼4 GHz) is observed through the use of a heterodyne down-conversion technique. Applications in atomic and plasma diagnostics are detailed.

The "reduction hypothesis" proposes that a product of nearby fluctuating local variables can be replaced by a linear combination of individual local variables. The linear combinations thereby produced are a kind of algebra of the reduction of products. A particular algebra is proposed for the two-dimensional Ising model. It is shown that a knowledge of which coefficients in the algebra are nonvanishing is sufficient to determine all critical indices.

The susceptibility of a thin-walled microcylinder is measured as a function of magnetic field at various temperatures, and oscillations due to fluxoid quantization are observed. In order to explain the magnetization close to $T_C$, where the phase transition is of second order, the expression for the flux in a thin-walled microcylinder derived by several authors must be used to relate the observed increments in magnetization to the absolute quantum of the fluxoid.

Measurements of the change in the velocity of sound of shear and compressional waves at the normal-to-superconducting transition have been made in a high-purity tin single crystal. The changes observed are of the order of a few parts in ${10}^4$, are electronic in origin, and agree qualitatively with theory for the shear-wave case.

We have studied the dynamics of the voltage-induced conductivity transition in magnetite at 78°K. We observe a time delay between the application of the voltage and the observation of the transition in conductivity, inversely proportional to the power applied to the sample. The mechanism of the transition is interpreted in terms of a Joule selfheating of the sample to the 119°K Verwey transition.

We have performed a variety of experiments on switching phenomena in a metal oxide, magnetite. Our findings are consistent with Joule microheating which drives the Verwey transition occurring at 119 K. We conclude that considerations of band structure, direct electric-field-induced transitions, tunneling, injection, and space-charge phenomena are not required to explain any of our observations.

We solve the Bubbard model, for one electron per atom in a simple cubic structure, using one-particle Green's functions. We determine the accuracy of this calculation to be good by comparison with an exact solution by Lieb and Wu of a one-dimensional limiting case. When the Coulomb interaction $U$ exceeds about 0.27 of the bandwidth in three dimensions we find there are two critical temperatures: $T_{\mathrm{N}}$, the Néel order-disorder transition temperature ($\propto U^{-1\mathrm{}}$ at large $U$) and a higher critical temperature $T_M$, at which the atoms lose all vestige of localized moments and at which the insulator-metal transition occurs ($T_M\propto U$ at large $U$). For $U$ less than 0.27 of the bandwidth only $T_M$ exists.

New measurements of the photoelectron energy distributions from cesiated Cu reveal structure not seen in previous data. The behavior of this new structure on varying the photon energy is characteristic of direct transitions. Theoretical calculations are presented which lend support to this conclusion.

The 1400-${\mathrm{cm}}^{-1\mathrm{}}$ absorption band of the nitrate impurity in potassium iodide shows at 4.2°K a considerable amount of fine structure. The intensity distribution of this fine structure is governed by the anharmonic coupling of the internal vibration of the nitrate ion with nearly unperturbed phonons. This distribution can be calculated satisfactorily by first-order perturbation theory.

An inherent magnetic-field quenching of Kondo scattering occurs via lifetime broadening of the spin-flipped intermediate states. This effect and other intrinsic features of the $s-d$ exchange problem are revealed by high-field tunneling studies of magnetic scattering.