We calculate the gravitational corrections to the Yang-Mills Chern-Simons term in three dimensions. Consistency requires the gravitational and the Yang-Mills mass parameters to be equal. Supersymmetry is used to relate previous results to each other.

We point out that local symmetries can masquerade as discrete global symmetries to an observer equipped with only low-energy probes. The existence of the underlying local gauge invariance can, however, result in observable Aharonov-Bohm-type effects. Black holes can therefore carry discrete gauge charges—a form of nonclassical ‘‘hair.’’ Neither black-hole evaporation, wormholes, nor anything else can violate discrete gauge symmetries. In supersymmetric unified theories such discrete symmetries can forbid proton-decay amplitudes that might otherwise be catastrophic.

The compact U(1) lattice gauge theory with dynamical fermions of mass m=0.1 and 0.05 with the gauge action ${\mathrm{\epsilon }}_{\mathit{P}}$(Βcos${\mathrm{\Theta }}_{\mathit{P}}$+ γcos2${\mathrm{\theta }}_{\mathit{P}}$) is studied numerically along phase-transition lines in the β,γ plane. On a $8^4$ lattice, discontinuities appearing in the internal energy and in the chiral order parameter 〈ψ¯ψ〉 at γ=0 are shown to vanish as γ decreases to negative values, indicating a existence of tricritical points. These results are compared with high-statistics data of the internal energy in the pure gauge theory on a ${16}^4$ lattice.

Realistic radiative quark and lepton masses for the first two generations, as well as mixing for all three, can be obtained in the context of the standard SU(2)⊗U(1) electroweak gauge model. The required additional ingredients are a fourth generation and some extra Higgs-boson doublets together with a singlet, as well as a spontaneously broken $Z_4$ discrete symmetry.

We calculate the complete set of O(${\mathrm{G}}_{\mathrm{F}}$${\mathrm{M}}_{\mathrm{H}}^2$) corrections to the elastic scattering of longitudinally polarized W bosons in the limit s,${\mathrm{M}}_{\mathrm{H}}^2$≫${\mathrm{M}}_{\mathrm{W}}^2$, for any value of s/${\mathrm{M}}_{\mathrm{H}}^2$. For any Higgs-boson mass such that ${\mathrm{M}}_{\mathrm{H}}$≫${\mathrm{M}}_{\mathrm{W}}$, there exists a critical energy above which partial-wave unitarity is violated and the one-loop correction to the J=0 partial wave is large, indicating the breakdown of perturbation theory.

We report a new measurement of the average lifetime of hadrons containing bottom quarks. The B-hadron decays are tagged by identifying leptons at high transverse momentum. From a fit to the lepton impact-parameter distribution, the average B-hadron lifetime is found to be (0.98±0.12±0.13)×${10}^{\mathrm{-}12}$ sec.

We have observed ${\Sigma }_c^{++}$ and ${\Sigma }_c^0$ baryons in nonresonant $e^{+}$$e^{\mathrm{-}}$ interactions through their decays to ${\Lambda }_c^{+}$${\pi }^{\pm }$ using the CLEO detector. The mass difference M(${\Sigma }_c^{++}$)-M(${\Lambda }_c^{+}$) is measured to be 167.8±0.4±0.3 MeV; for M(${\Sigma }_c^0$)-M(${\Lambda }_c^{+}$) we find 167.9±0.5±0.3 MeV. ${\Sigma }_c$ decay accounts for (18±3±5)% of ${\Lambda }_c^{+}$ production.

Linear relations between the partial-wave amplitudes for nucleon-nucleon scattering are derived from the assumption that the interactions respect K symmetry, which is a combination of isospin and angular momentum. The linear relations are tested using partial-wave amplitudes from phase-shift analyses and are found to be reasonably well satisfied at intermediate energies.

We consider interference effects in the inclusive emission of two identical particles from a compound nucleus. Statistical assumptions result in a correlation of the emitted particles that depends upon the coherence properties of the level widths in a form similar to that describing fluctuations in an exclusive cross section. A schematic application to the decay of a rapidly rotating compound nucleus shows that the observed source size can depend upon the kinematics of the measurement.

Triple differential cross sections of charged pions were measured for collisions of Ne projectiles at E/A=800 MeV with NaF, Nb, and Pb targets. The reaction plane was estimated event by event from the light-baryon momentum distribution. For heavy targets, preferential emission of charged pions away from the interaction zone towards the projectile side was observed in the transverse direction. Such a preferential emission, which is not predicted by cascade calculations, may be attributed to a stronger pion absorption by the heavier spectator remnant.

Cross sections for the fusion of ${}_{}{}^{10}{}_{}{}^{}$,11B${+}^{10}$,11B have been measured in the energy range from 1.5 to 5 MeV/nucleon. The ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ system unexpectedly presents a hindered fusion cross section when compared to the ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ reactions and to standard model predictions. The missing fusion cross section was diverted to the ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ exit channel with a total kinetic energy characteristic of strongly damped collisions. Q values and kinematical analysis together with angular distributions suggest a binary symmetric decay of the composite ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ system.

In the long-wavelength limit, above-threshold ionization (ATI) is primarily the result of the interaction of a newly freed electron with the laser field. Classical physics requires that linearly and circularly polarized light produce very different ATI spectra. Measurements performed using both linearly and circularly polarized, picosecond, 10-μm pulses confirm these conclusions.

Unidirectional, efficient up-conversion to the anti-Stokes wave has been attained in stimulated rotational Raman scattering by introducing optical switching of the pump polarization. Generation of an anti-Stokes power as high as the pump power was demonstrated by means of fast turnover of the rotating direction of the circularly polarized pump pulse. The results are explained by unique coupling between the phonon and pump waves.

We report on the measurement of density-sensitive electric quadrupole transitions in neonlike molybdenum and silver laser-produced plasmas. These observations are unique in that they represent data which are simultaneously space and time resolved. The electron densities were determined using holographic interferometry. We test the predicted density sensitivity of the electric quadrupole transitions and find excellent agreement with calculations using a detailed, steady-state, collisional-radiative model of the neonlike charge state.

We study numerically the laminar fully developed region of periodic flows through curved pipes. Under certain conditions the results exhibit period tripling. This striking feature is reminiscent of one of the possible routes to chaos which typical nonlinear dynamical systems take.

We show experimentally the appearance of time-dependent and stationary complex spatial structures in a ${\mathrm{CO}}_2$ laser. A comparison of the data with a theoretical model supports the notion that the observed phenomena result from the nonlinear interaction of transverse cavity modes with the active medium. The simultaneous appearance of spatial and temporal instabilities hints to the interesting prospect that one may be able to study turbulence in a laser system.

A volume average toroidal β of 6.2% has been obtained with 10 MW of hydrogen neutral beam injection into deuterium divertor discharges in DIII-D. High-β discharges were maintained quiescently for many energy confinement times in elongated, κ=2, divertor discharges where the safety factor at the 95% flux surface was near 2. The maximum β calculated to be stable against ideal kinks and ideal ballooning modes is 8.5%–9.5%, confirming that these I/aB≊2.5 MA/m T discharges are some distance below the stability limit.

Saturation or slow collapse of β is observed in DIII-D divertor discharges at high-values of normalized β [(β/(I/aB)≥2.4]. The sequential appearance of MHD instabilities with poloidal/ toroidal mode numbers m/n=5/4, 4/3, 3/2, and 2/1 at progressively larger minor radii leads to the saturation or collapse of β. Only n=2 and n=1 modes affect global energy confinement. A model is suggested in which the instabilities originate as high-n ballooning modes near the center of the discharge, progressing to lower-n modes by modification of pressure and current profiles.

Via ellipsometry, we study the profile evolution of very small drops (about ${10}^{\mathrm{-}4}$ μl) of nonvolatile liquids, spreading completely on silicon wafers. The evolution of the profiles are studied at molecular thicknesses, and for the first time it is shown that (i) the final stage of spreading in the cases studied is not a pancake, as predicted by the theory of de Gennes and Joanny (for S/γ≪1), but rather is a two-dimensional gas and (ii) short-range forces and molecular dymanics may drastically affect the profile of the droplet.

A model for film growth from hyperthermal (≊1–${10}^3$ eV) species impinging on substrates is proposed. The process includes subsurface implantation, energy loss, preferential displacement of atoms with low displacement energies ($E_d$) leaving high $E_d$ atoms undisplaced, and sputtering of substrate material. Epitaxial growth and preferred orientation result from the angular dependence of the $E_d$ and the host mold effect. The model, supported by ion trajectory calculations and experimental data, is applied to diamond film formation from ${\mathrm{C}}^{+}$ ions.