A superconducting proximity effect existing in a two-dimensional electron gas in the native inversion layer on a $p$-type InAs substrate has been confirmed. A supercurrent in the inversion layer was observed for the first time, in addition to an ac Josephson effect, with superconducting electrodes separated by 0.2-0.5 μm. The coherence lengths obtained coincide well with each other, both experimentally and theoretically. A junction with a metal gate electrode showed the controllability of the supercurrent by the gate voltage.

We report experimental results on the broadband noise in the sliding—charge-density-wave conductor, orthorhombic Ta${\mathrm{S}}_3$. We propose that the noise has its origin in the interaction of a deformable condensate with random impurities. The experimental results are in excellent agreement with a phenomenological model based on fluctuations in the impurity pinning force due to deformations of the sliding condensate. The amplitude of the noise is directly related to the dynamic coherence volume of these deformations.

We point out a possibility of temporal charge nonconservation in cosmological models based on more-dimensional theories a là Kaluza-Klein. A net excess charge may then have been created before the extra dimensional space was compactified. Cosmological implications of the excess charge are discussed.

The dielectric-plasma transition of the two-dimensional Coulomb gas, suitably mapped onto a delocalization transition, is investigated by molecular-dynamics simulations. The threshold temperature $T_1$ for electrical conduction falls well below the temperature $T_2$ associated with a marked peak in the specific heat; $T_2$ is close to the mean-field prediction for the Kosterlitz-Thouless transition, $\frac{k_{\mathrm{B}}{T}_2}{e^2}=\frac{1}{4}$.

A ${\phi }^3$ field theory in a six-dimensional conformally flat space-time is studied at the two-loop level. It is found that the state-dependent divergences do not cancel and thus the theory does not become renormalized in the usual way.

Any model in which the neutrino mass matrix violates the Glashow-Iliopoulos-Maiani mechanism can give monojets. The $Z$ can decay into one heavy and one light neutrino, with the heavier neutrino decaying into a jet. If the heavier neutrino is sufficiently light, this mechanism has not been ruled out by recent searches at PEP and PETRA for monojet signatures. Such monojets arise naturally in the SO(18) model of family unification. In this model we predict additional unusual events, which result from the purely leptonic decay of the heavier neutrino.

We report results of a search for events of the type $e^{+}{e}^{-}\to \mathrm{jet}+\mathrm{missing}\mathrm{transverse}\mathrm{momentum}$ using the Mark II detector at PEP. Two candidate events were found, but both could come from known sources of background. A specific model for the origin of UA1 monojet events as the decay of a $Z$ boson into two light Higgs bosons is eliminated by this search.

It is shown that in a gauge theory on an $L^d$ lattice with a compact Lie group, the weak-coupling expansion of any gauge-invariant Green's function may cease to be an asymptotic representation of the true answer as $L\to \infty$. The disagreement is expected to occur at the two-loop level, in non-Abelian models.

The valence quark $a$ is postulated to respond, when probed by a soft photon, with the outward effective mass defined by the relation $m_a^B=M_B-m_b-m_c$, where $M_B$ is the physical mass of baryon $B$, and $m_b$ and $m_c$ are the effective masses of the spectator valence quarks $b$ and $c$ in the usual sense. The observed characteristics of baryon magnetic moments are shown to be well described in the naive scheme of the additive quark model if the new notion of the outward effective mass of quarks is incorporated.

We study the distributions of 135 atmospheric neutrino events collected in 420 days of running in a large, deep underground detector. These events come from neutrinos with path lengths ranging from a few kilometers to over ${10}^4$ kilometers. The average neutrino energy is 920 MeV. No evidence for neutrino oscillations is observed. Flux-independent limits for $\Delta m_{\nu }^2$ in the range of 2.2×${10}^{-5\mathrm{}}$ to 11.2×${10}^{-5\mathrm{}}$ e${\mathrm{V}}^2$ are set for maximum mixing.

A recent observation of a 17-keV neutrino in tritium beta decay can be incorporated into the standard model with just three light neutrinos. Constraints on neutrino masses suggest that the lepton mass matrices have an approximate global symmetry which results in two of the three neutrinos having masses near 17 keV. A prediction for the mixing angle in ${\nu }_e\to {\nu }_{\tau }$ oscillations is made. Cosmological constraints on the 17-keV neutrino are discussed. Models with majorons or familons are found to be attractive possibilities.

Spontaneously broken $B-L$ symmetry can produce cosmologically safe massive neutrinos such as may have been observed as well as trimuons at CERN.

A lower limit of 1.16×${10}^{23}$ yr ($1\sigma$) is reported for the half-life of no-neutrino ${\beta }^{-}{\beta }^{-}$ decay of ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$ which results from 3763 h of counting with an ultralow-background, 135-${\mathrm{cm}}^3$ prototype detector located 1438 m underground. A limit of 1.7×${10}^{23}$ yr ($1\sigma$) results from the best combination of our data with that from other experiments. Straightforward application of shell-model matrix elements to this limit implies that $〈m_{\nu }〉<3.2\mathrm{}$ eV ($1\sigma$).

Energy-level fluctuations are calculated by random-matrix methods, for time-reversal noninvariant (TRNI) Hamiltonians. The theory, applied to the data, shows that in the neutron and proton resonance regions (i.e., for heavy and intermediate nuclei, respectively), the local rms off-diagonal multiparticle $H\left(\mathrm{TRNI}\right)$ matrix element $\lesssim \frac{D}{10}$, with $D$ the level spacing. Spectral averaging methods reduce this to a bound on the nucleon-nucleon TRNI vs TRI interactions. First calculations, for ${}_{}{}^{169}{}_{}{}^{}\mathrm{Er}$, give a 1% upper bound.

We have investigated the $K$-shell electron-capture decay of ${}_{}{}^{158}{}_{}{}^{}\mathrm{Tb}$, and, contrary to an earlier claim, we find no evidence for $K$ capture to a state at 1187 keV. Our results are consistent with recent measurements of related reaction $Q$ values and invalidate the claim that ${}_{}{}^{158}{}_{}{}^{}\mathrm{Tb}$ decay is useful for determining the mass of the neutrino.

On the basis of microscopic models for $s$-wave pion absorption on nucleon pairs the contribution of $T=1\mathrm{}$ pairs compared to $T=0\mathrm{}$ pairs should be strongly suppressed. A direct consequence, not previously noted, is that the $1s$ absorption widths in the pionic atoms ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ should be equal, aside from renormalization due to the different ${\pi }^{-}$-atomic wave-function length scales. The ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ width, which is not directly observable, is thus predicted to be 2.25 ± 0.55 eV. It is shown that this value is consistent with observed branching ratios for radiative capture in the mirror pair.

The empirical distributions of Gamow-Teller strengths in ${}_{}{}^{98}{}_{}{}^{}\mathrm{Tc}$ and ${}_{}{}^{115}{}_{}{}^{}\mathrm{Sn}$ have been obtained via the ($p, n$) reaction at $E_p=120\mathrm{}$ MeV and $E_p=200\mathrm{}$ MeV on ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$ targets. This information is used to calculate the cross sections for absorption of solar neutrinos in ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$, nuclides which are being considered as neutrino detectors to accomplish solar-neutrino spectroscopy.

The long-time behavior of the number of photons in a mode of the electromagnetic field is given in closed form in terms of elementary functions when there is initially one (two-level) atom excited in the presence of $N$ unexcited identical atoms and $M$ field modes. The radiation trapping which occurs with only one mode disappears when the number of modes $M$ approaches the total number of atoms in the continuum mode approximation.

Arising in the modeling of both magnetohydrodynamical equilibria and Alfvén-wave heating in nonaxisymmetric toroidal plasmas is a one-dimensional quadratic Hamiltonian with periodic coefficients. We establish the existence of a class of single-valued invariants and address the stability of solutions to the Hamiltonian system.

Single-component plasmas are found to exhibit a reversal in the roles of cyclotron and upper hybrid resonances familiar in neutral plasmas. There is a global resonance at the cyclotron frequency $\omega =\Omega \equiv \frac{\mathrm{qB}}{\mathrm{mc}}$ and a local field cancellation at layers where $\omega ={\Omega }_1={({\Omega }^2-{\omega }_p^2)}^{\frac{1}{2}}$, ${\omega }_p$ being the local plasma frequency. Thermal effects limit the amplitude of the global resonance and produce energy absorption at the $\omega ={\Omega }_1$ layers.