It is shown how to obtain the Dirac commutator, $\mathrm{}[x,p]=i\hslash$, from the London-Weyl formalism.

An effective-spin model for finite-temperature QCD is derived by use of a variant of the Migdal-Kadanoff renormalization group. Mean field theory and [for SU(3)] Monte Carlo simulation are applied to the model in order to find the deconfining phase transition. The results are in very good agreement with Monte Carlo simulations of the full theory. Mean field theory predicts that the deconfining transition in pure $\mathrm{SU}\mathrm{}\left(N\right)\mathrm{}$ lattice gauge theory is first order for all $N>~3$.

A search for massive moving magnetic monopoles has been performed with a combined detector of proportional chambers and scintillation counters. Mixed gas of helium and 10% methane was used for the proportional chambers, because ionizations occur by the Drell mechanism and the Penning effect. No candidate for the monopole was obtained during 150 days of live time. The upper flux limit of 7.2×${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$ for monopoles is obtained for the velocity range from $\sim 3\times {10}^{-4\mathrm{}}c$ to $1c$ at a 90% confidence level.

A general quartic potential invariant under a group $G$ and containing any number of scalar fields in arbitrary representations is shown to have a mass spectrum at the symmetrybreaking global minimum satisfying $\Sigma A^{}{M}_A^2{v}_A^2<~2\lambda {\left(\Sigma A^{}{v}_A^2\right)}^2$, where $v_A$ is the vacuum expectation value of the $A\mathrm{th}$ mass eigenfield with any singlet removed. For SU(2) ⊗ U(1) with arbitrary Higgs particles this guarantees that the lightest neutral scalar boson will satisfy $M_{min}^2<~\frac{\lambda \sqrt{2}}{G_{\mathrm{F}}}=\lambda {\left(350\mathrm{} \mathrm{GeV}\right)}^2$ where $\lambda$ is a particular quartic coupling constant.

We have measured the proton-air inelastic cross section at $s^{\frac{1}{2}}=30\mathrm{}$ TeV by observing the distribution of extensive-air-shower maxima as a function of atmospheric depth. This distribution has an exponential tail whose slope is $\lambda =72\mathrm{}\pm 9$ g ${\mathrm{cm}}^{-2\mathrm{}}$ which implies that ${\sigma }_{p-\mathrm{air}}^{\mathrm{inel}}=530\mathrm{}\pm 66$ mb. Using Glauber theory and assuming that the elastic-scattering slope parameter $b$ is proportional to ${\sigma }_{\mathrm{pp}}^{\mathrm{tot}}$, we infer a value of ${\sigma }_{\mathrm{pp}}^{\mathrm{tot}}=120\mathrm{}\pm 15$ mb which lies between a $logs$ and a ${log}^{2}s$ extrapolation of the total $\mathrm{pp}$ cross section as measured at lower energies.

A search for inclusive muon-neutrino (${\nu }_{\mu }$) oscillations has been performed in the Fermilab narrow-band neutrino beam using two detectors running simultaneously at two distances from the neutrino source. The data show no evidence for a distance dependence of the neutrino flux and rule out oscillations of ${\nu }_{\mu }$ into any other single type of neutrino for $30<\mathrm{}\Delta m^2<1000\mathrm{}$ ${\mathrm{eV}}^2$/${\mathit{c}}^4$ and ${sin}^2\left(2\mathrm{}\theta \right)>\mathrm{}0.02-0.20\mathrm{}$.

Parity nonconservation in weak $\mathrm{nd}$ scattering is studied at threshold where neutron spin rotation might occur. The standard (Faddeev) three-body theory with an $s$-wave separable potential is employed together with modifications introduced to account for the weak $\mathrm{NN}$ interaction, for which I take the one-pion-exchange isovector term. I find $\frac{d\phi }{\mathrm{dz}}=6.13\mathrm{}\times {10}^{-9\mathrm{}}$ rad/cm and estimate the errors resulting from the adoption of the pertinent approximations.

We estimate the baryon distribution in highly relativistic heavy-ion collisions in order to determine the baryon impurity of the quark-gluon plasma in the central rapidity region. In the energy range of $\frac{s^{\frac{1}{2}}}{A}\sim 30-100$ GeV per nucleon, the degree of impurity, which can be improved slightly with increasing bombarding energy, is a few percent in energy density.

We show that the rapidity analysis of ($\pi$,$p$) inclusive data on nuclei measures not only the number of nucleons coherently involved in pion absorption, but also the mean momentum loss due to incoherent multiple scattering. We use a statistical theory to calculate the mean momentum loss, also reproducing the inelastic and absorption cross sections. The ($\pi$,$p$) rapidity data can be reproduced with a $2N$ absorption mechanism, but not with larger clusters, in contrast to earlier analysis which neglected multiple scattering before absorption.

We performed an experiment using plastic nuclear track detectors to investigate the phenomenon of enlarged cross sections for projectile fragments of relativistic ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ nuclei. This effect had been observed within the first few centimeters after fragment emission in Bevalac and cosmic-ray experiments with nuclear emulsion. On the basis of 6444 charge-changing nuclear collisions we conclude that under our experimental conditions no statistically significant anomalous mean free path effect can be observed.

The multiplicity, anisotropy, and circular polarization of the $\gamma$ radiation from 270-MeV ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ + ${}_{}{}^{168}{}_{}{}^{}\mathrm{Er}$ were measured in coincidence with the projectilelike fragments. The deduced angular momentum transfer in the deep-inelastic reaction component is rather small but can be understood, together with the fluctuations of the spin axis and the prevalence of negative-angle scattering, in terms of a frictional process in concurrence with breakup.

Excitations of a $T=0\mathrm{}$ and nine $T=1, 1^{+}$ states have been observed in the reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}(p,p^{\prime })$ at 201 MeV. The magnitudes of the measured cross sections of the isoscalar and isovector transitions are, respectively, about 24% and 33% of predictions obtained with fullbasis $\mathrm{sd}$-shell-model wave functions. The large reduction factor in the isoscalar channel, where $\Delta$-isobar effects must be insignificant, suggests that higher-order configuration mixing must be an important source of quenching in both isoscalar and isovector channels.

The recently discovered ${\mathrm{He}}_2^{-}$ ion is examined by means of configuration-interaction wave functions constructed from an extended Slater-type-orbitals basis. We find that the ${}_{}{}^4{}_{}{}^{}\Pi _g^{}{}_{}{}^{}$ state of ${\mathrm{He}}_2^{-}$ is bound relative to the $a{}_{}{}^2{}_{}{}^{}\Sigma _{\mathrm{u}}^{+}{}_{}{}^{}$ state of ${\mathrm{He}}_2$. The calculated electron affinity is 0.233 eV compared to 0.077 eV for the ${\mathrm{He}}^{-}\left[{}_{}{}^4{}_{}{}^{}P_{}^{\circ }{}_{}{}^{}\right]$ ion. This anion decays through the long-lived $\frac{5}{2}\mathrm{g}$ component with $\tau \sim 350$ μsec and the much shorter-lived $\frac{3}{2}\mathrm{g}$, ½g components with $\tau \sim 10$ μsec.

Total cross sections ($Q_T)$ for 1-500-eV positron and electron scattering by ${\mathrm{N}}_2$O are measured by a beam-transmission method. Comparisons of these results with prior electron and positron measurements of $Q_T$ for C${\mathrm{O}}_2$, ${\mathrm{N}}_2$, and CO, made by our group, reveal several remarkable similarities in the shapes and magnitudes of the $Q_T$ curves for the triatomic and also for the diatomic molecules. Small differences in the absolute $Q_T$ values for ${\mathrm{N}}_2$O and C${\mathrm{O}}_2$, and for ${\mathrm{N}}_2$ and CO, may be due to the weak permanent dipole moments of ${\mathrm{N}}_2$O and CO.

When a trough resonator partially filled with water is parametrically driven at an appropriate frequency and amplitude, one or more surface-wave solitons with polaronlike behavior are created. Their properties and interactions are described.

It is shown that the negative mass instability in a rotating relativistic electron layer may be stabilized by a radial dc electric field of a suitable magnitude. The stabilization mechanism is independent of the beam velocity spread, and is insensitive to the beam current, the container geometry, or the azimuthal mode number. A simple stability criterion is given.

It is shown that the upper critical dimension $d^{*}$ for complete wetting is $d^{*}=3\mathrm{}$ for shortrange forces and $d^{*}<3\mathrm{}$ for long-range forces. The critical exponent ${\nu }_{\parallel }$ for the divergence of transverse correlations at complete wetting in three-dimensional systems is found to be ${\nu }_{\parallel }=\frac{1}{2}$ for short-range forces and ${\nu }_{\parallel }=\frac{2}{3}$ for long-range forces of van der Waals type.

We use transmission-electron micrographs to study the structure formed by the irreversible kinetic aggregation of uniformly sized aqueous gold colloids. The structures are highly ramified and exhibit a scale invariance that is well described as a fractal with a Hausdorff dimension of ∼ 1.75. This value is in excellent agreement with recent computer simulations of diffusion-limited aggregation when the clusters themselves are allowed to aggregate.

A low-symmetry twofold bridge site of (2×1) oxygen on Cu(110) allows the determination of the azimuthal dependence of the surface extended x-ray—absorption fine structure. For normal incidence and $\overrightarrow{\mathrm{E}}$ parallel to the [100] and [110] directions we determine the nearest- and second-nearest-neighbor distances to be 1.84(2) and 2.00(5) Å, respectively. We show that the atomic oxygen is occupying the low-symmetry twofold bridge site in the [100] direction 0.35 Å above the first Cu layer.

We present a model for the relaxation of the magnetization of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in contact with a solid substrate, leading to an explanation of the generally seen linear dependence of $T_1$ on temperature. The temperature dependence of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ relaxation time results from the localization of the relaxation to the interfacial layer of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. The model, tested for experiments on a fluorocarbon substrate, fits the data over three decades of temperature, with one adjustable parameter.