When a parameter in the Hamiltonian of a one-degree-of-freedom oscillator is slowly varied at rate $\epsilon$, an adiabatic invariant exists which is conserved to all orders in $\epsilon$, except on phase-space orbits which cross a separatrix. In the present work, the change in the adiabatic invariant due to a separatrix crossing is given to order $\epsilon$ for a wide class of Hamiltonian systems. This result is applied to the special case of a charged particle moving under the influence of an electrostatic wave with slowly varying amplitude and frequency.

The contribution of a $\mathrm{CP}$-nonconserving nucleon-nucleon interaction to the electric dipole moment of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is evaluated in view of a recent proposal for its experimental detection. We use two models of $\mathrm{CP}$-nonconserving interactions in combination with a Reid soft-core strong nucleon-nucleon interaction. In the Kobayashi-Maskawa model of $\mathrm{CP}$ nonconservation the order of magnitude is ${10}^{-30\mathrm{}}$ e cm while the presence of the $\theta$ term in the QCD Lagrangean contributes an order of magnitude ${10}^{-16\mathrm{}}\theta$ e cm.

We discuss a class of lattice gauge-Higgs models with local ⊗ global symmetry groups and present an exact solution for a class of 2D theories. The latter constitute the first nontrivial exactly solved lattice gauge-Higgs models.

It has been suggested that pair annihilation of heavy Majorana fermions in the galactic halo into quarkonium plus a monochromatic photon could occur at an observable rate. Here we show that a calculation of Srednicki, Theisen, and Silk seriously overestimates the rate for this process, by an order of magnitude or more, as a result of neglecting the bound-state structure of quarkonium. It may nevertheless still be possible to resolve the correspondingly smaller gamma-ray line flux over the diffuse cosmic background by use of the currently planned space-borne superconducting-magnet spectrometer facility with an energy resolution of 1% or better.

We report the results of a study of the three-prong decay mode of the $\tau$ in data taken with the DELCO detector at the SLAC $e^{+}{e}^{-}$ storage ring PEP. We determine the total three-prong branching ratio to be $B\left(3\right)=(12.1\mathrm{}\pm 0.5\pm 1.2)\%$ and the exclusive branching ratios $B(\tau \to {\pi }^{+}{\pi }^{-}{\pi }^{\pm }\nu )=(5.0\mathrm{}\pm 0.1)\%$ and $B(\tau \to {\pi }^{+}{\pi }^{-}{\pi }^{\pm }{\pi }^0\nu )=(6.0\mathrm{}\pm 1.2)\%$, respectively. The data with three charged pions allow for the determination of the mass and width of the $A_1$ resonance as $M_{A_1}=1056\mathrm{}\pm 20\pm 15$ MeV and ${\Gamma }_{A_1}={476}_{-120\mathrm{}}^{+132\mathrm{}}\pm 54$ MeV.

The weak hadronic decay $D^0\to {\overline{K}}^0{K}^{+}{K}^{-}$ is observed in a data sample of 9.3 ${\mathrm{pb}}^{-1\mathrm{}}$ collected with the Mark III detector at the $\psi \mathrm{}\left(3770\right)\mathrm{}$ resonance. An analysis of the $K^{+}{K}^{-}$ subsystem suggests that while the decay proceeds in part through the ${\overline{K}}^0\phi$ channel, providing evidence for the presence of nonspectator amplitudes in $D^0$ decays, a significant fraction of the decays occurs through both higher- and lower-mass $K^{+}{K}^{-}$ systems. A limit is set on the decay $D^0\to {\overline{K}}^0{K}^0$, also thought to proceed by nonspectator processes.

A new technique is applied to data collected at the $\psi \mathrm{}\left(3770\right)\mathrm{}$ resonance to derive charmed-$D$-meson branching fractions without relying on the measurement of $D$-production cross sections. Measurements are presented for three decay modes of the $D^0 (K^{-}{\pi }^{+}, D^{-}{\pi }^{-}{\pi }^{+}{\pi }^{+}, \mathrm{and} K^{-}{\pi }^{+}{\pi }^0$ and four decay modes of the $D^{+} (K^{-}{\pi }^{+}{\pi }^{+},K^{-}{\pi }^{+}{\pi }^{+}{\pi }^0,K_S^0{\pi }^{+}, \mathrm{and} K_S^0{\pi }^{+}{\pi }^0)$. The resulting branching fractions are significantly larger than previous measurements.

An alternative covariant formulation of string field dynamics is given, in which functions of one-dimensional curves (line functionals) are the essential ingredients. Guided by the geometrical principle of manifest reparametrization invariance and the correspondence to Nambu-Goto string dynamics in the $x^0=\tau$ gauge, we derive generalized Dirac-string field equations linear in the momentum density. It is shown that in three dimensions the equations for closed strings admit an equally spaced mass-squared spectrum, including massless particles of spin 0 and 1.

The compactifications of the ten-dimensional Einstein-Maxwell theory and the Einstein-Maxwell-scalar theory into $M_4\times S^2\times S^2\times S^2$, where $M_4$ denotes four-dimensional Minkowski space, are found to be unstable.

Under the assumption that the quarks and the Higgs boson are composites, it has been argued that the third $\tau$ family is expected, on rather general grounds, to have an inverse size of order only 1 TeV. We note that the study of $e^{-}{e}^{+}\to t-\mathrm{quarkonium}\to {\tau }^{-}{\tau }^{+}$ would be especially suitable to observe this compositeness already at energies of the CERN large electron-positron collider ring (LEP), assuming that $m_{\mathrm{top}}\lesssim 50$ GeV.

The cross sections for the production of charged pions and protons from the annihilation of 608-MeV/c antiprotons on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ are presented. The sources of pion and proton emission are inferred from the rapidity distributions of the data. The results are compared to and seen to be in good agreement with intranuclear-cascade calculations.

This paper reports the first theoretical calculations of alignment and orientation of the electron cloud of the $\mathrm{Li}\left(2^{2}P\right)$ and $\mathrm{He}\left(2^{1}P\right)$ states excited by $2p\sigma -2p\pi$ rotational coupling in ${\mathrm{Li}}^{+}$ + He collisions at energies from 0.8 to 25 keV. The molecular-orbital-expansion method is used with specific inclusion of the molecular-electron-translation factor. Calculations made with this method are found to be in very good accord with the recent measurement.

The line shape of the Raman transition between metastable levels of neon (${}_{}{}^3{}_{}{}^{}p_0^{}{}_{}{}^{}\mathrm{and}{}_{}{}^3{}_{}{}^{}p_2^{}{}_{}{}^{}$) is studied as a function of the pressure of a helium buffer gas. Dicke narrowing of the Doppler-broadened nonresonant Raman signal (for large optical detunings) gives the first evidence of conservation of a fine-structure coherence by velocity-changing collisions. Pressure broadening of the resonant Raman signal gives a measurement of the velocity-changing-collision rate.

The results of total-energy calculations for optimized structures of ${\mathrm{Al}}_n \mathrm{}(n=2-6\mathrm{})\mathrm{}$ and ${\mathrm{Al}}_n{\mathrm{H}}_2$ are presented in which properties are found to be at variance with the predictions of the electronic shell model. These differences are understood by the introduction of atomic potentials as a perturbation on the shell model. Ionization energies (5.8-6.6 eV) and electron affinities (0.1-2.1 eV) are mostly larger than for an Al atom. Bond lengths increase from 2.51 to 2.81 Å. ${\mathrm{Al}}_6$ is found to be the smallest cluster that will adsorb ${\mathrm{H}}_2$.

In 1984 Erpenbeck observed a shear-induced alignment of particles into strings in nonequilibrium molecular-dynamics simulations of shear flow in the hard-sphere fluid. In this paper we show that this effect arises from the use of a thermostat which assumes a stable linear velocity profile. The use of a thermostat which does not bias the streaming velocity profile causes the string phase to vanish.

Near-photon-number-eigenstate fields lead to dramatic signal-to-noise improvement beyond the standard shot-noise limit in many optical systems, including interferometric gravitational-wave detectors. These fields may be generated from parametric processes with measurement feedback. Degradation from nonideal photodetection can be overcome by appropriate optical preamplification. It is estimated that an order-of-magnitude improvement can already be obtained with existing devices.

By injection of microwave power $P_{\mathrm{EC}}$ near the electron cyclotron (EC) frequency into an Ohmically heated (OH) plasma in the WT-2 tokamak after OH power is shut off, the plasma current is sustained and ramped up by the EC wave only, without OH power. Here, EC-driven current is generated by EC heating of the suprathermal electron beam in OH plasma. Further, when $P_{\mathrm{EC}}$ is injected into plasma sustained by lower-hybrid- (LH-) driven current, the plasma current and its rampup rate increase. Here, EC-driven current is generated by EC heating of the mildly relativistic electrons in LH-driven plasma.

A differential density probe is used to study the angular distribution of ion acoustic waves produced by parametric decay instabilities. The measured results show that just after the pump field is turned on, the angular distribution is significantly peaked in the direction of the pump field, as expected. However, the distribution evolves in time to become almost isotropic. The characteristic time for this process decreases with pump power. For high powers, the spectrum becomes almost isotropic in about two ion acoustic periods ($\sim \frac{4\pi }{{\omega }_s}$), in reasonable agreement with theoretical predictions.

Both in Ohmically and beam-heated $L$-mode discharges of ASDEX, the electron-temperature ($T_e$) profile shape can be varied over a wide range by the choice of the safety factor $q_a$. The power-deposition profile, on the contrary, has no effect on the $T_e$ profile shape. In current-free W-VII-A stellarator plasmas, no such invariance property is found. An independent constraint seems to fix the current distribution $j\left(r\right)\mathrm{}$ of the tokamak, which defines the conditions of electron heat transport.

The stability of icosahedral, pentagonal, and other quasicrystalline phases to deformations which make them commensurate, and thus periodic, in one or more directions is analyzed. Although such deformations may be arbitrarily small, it is shown that quasicrystals are generically stable to them. Quasicrystals may therefore exist as thermodynamically stable phases. The possible symmetries which may arise in icosahedral structures when these deformations do take place are considered.