We point out difficulties with our proposed local quantum field theory of small violations of the Pauli principle and give a qualitative rationale for the surprising rigidity of the exclusion principle.

We argue that the $\beta$ function for the statistics parameter in (2+1)-dimensional electrodynamics is zero to all orders in perturbation theory beyond one loop. We show that there can be finite radiative corrections from massless charged scalar fields.

Attention is drawn to the fact that if the fourth family exists then the decay of the charge $-\frac{1}{3}$ member quark ($b^{\prime }$) may be a very rich source for production of the standard-model Higgs particle. While definitive numerical predictions are not possible at present since values of masses and mixings are unknown, we find that for $m_{b^{\prime }}\lesssim 100$ GeV the mode $b^{\prime }\to b+H$ can be a very important decay, if not the dominant decay, of the $b^{\prime }$. Experimental consequences for hadronic and for $e^{+}{e}^{-}$ colliders and strategies for the detection of this elusive particle are discussed.

The decay $D^{+}\to K^{-}{\pi }^{+}{e}^{+}{\nu }_e$ has been studied in the Fermilab photoproduction experiment E691. The ratio of branching ratios, $\frac{B(D^{+}\to {\overline{K}}^{*0\mathrm{}}{e}^{+}{\nu }_e)}{B(D^{+}\to K^{-}{\pi }^{+}{\pi }^{+})}$, is found to be 0.49±0.04 ±0.05, corresponding to a $D^{+}\to {\overline{K}}^{*0\mathrm{}}{e}^{+}{\nu }_e$ branching ratio of (4.5±0.7±0.5)%. The branching ratio to the nonresonant ${\left(K^{-}{\pi }^{+}\right)}_{\mathrm{NR}}e{\nu }_e$ final state is found to be less than 0.7% at the 90% confidence level. The ${\overline{K}}^{*0\mathrm{}}$ mesons have a ratio of longitudinal to transverse polarization of 2.4${\pm }_{0.9}^{1.7}$±0.2.

The next-to-leading-order jet cross section is calculated for the simplified case in which there are only gluons. The general structure of the differences from the lowest-order cross section are described. The important new effects at this order are the explicit dependence on the definition of the jet and the reduced dependence on the choice of the renormalization scale ${\mu }^2$. While only the purely glue results are discussed here, we expect that the dependence on the jet definition and on ${\mu }^2$ will be quite similar in the complete calculation, which we are now undertaking.

We discuss double scattering in high-transverse-momentum cross sections on nuclei in the context of QCD. We give results for the $A$ dependence of jet and one-particle inclusive cross sections in hadron and lepton reactions, in terms of the distribution of gluons in a bound nucleon.

The method of scaled factorial moments is used to study short-range fluctuations in the pseudorapidity distributions of particles produced in high-energy interactions in nuclear emulsion. An intermittent behavior of the fluctuations is clearly observed in both proton (200 and 800 GeV) and oxygen (60 and 200 GeV/nucleon) beam interactions in emulsion.

The observed differences in kinetic and chemical temperatures in heavy-ion reactions is addressed by means of a computer simulation. Focusing on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ nuclei emitted at wide angles, we find that the chemical temperatures show no strong variation with laboratory bombarding energy between 35 and 100 MeV/nucleon. Further, the chemical temperature is found to be in the 3—4-MeV range, much lower than the kinetic temperature and consistent with experiment. The difference in the two temperatures is established after a fairly short time scale roughly corresponding to the breakup time of the reaction region.

Angle-resolved energy spectra of ejected electrons have been measured following the decay of autoionizing states created by slow ${\mathrm{Na}}^{+}$ impact on Ne. Spectral structures with two major peaks due to molecular and atomic autoionization have been observed at the ion impact energy of 200 eV. Remarkable substructures have been found in the lower-energy wing of the atomic autoionization peak. These substructures are associated with quantum beats due to the interference between the coherent autoionizing transitions of the doubly excited state to the doublet substates ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ and ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ of ${\mathrm{Ne}}^{+}\left(2\mathrm{}{p}^5\right)$.

By using S${\mathrm{O}}_2$ as a prototype molecule, negative fragment ions are produced by photon excitation in the vicinity of its sulfur $2p$ core-ionization (≃175 eV) and direct-double-ionization (≃34.1 eV) thresholds. This new class of processes is shown to be at least partly related to the existence of superexcited electronic states of the singly charged parent cation lying above the double-ionization-threshold energy. The use of these mechanisms as a specific tool for probing the nature and the relaxation of core-excited states of molecules is also illustrated.

Using concentrations of vorticity along the interface, a new model is proposed for the development of the Rayleigh-Taylor instability in the Boussinesq limit. The accuracy of the model is assessed by comparison with full numerical simulations.

A Stieltjes integral representation for the effective diffusivity in turbulent transport is developed. This formula is valid for all Peclet numbers and yields a rigorous resummation of the divergent perturbation series in Peclet number provided that all diagrams are computed exactly. Another consequence of the integral representation is convergent upper and lower bounds on effective diffusivity for all Peclet numbers utilizing a prescribed finite number of terms in their perturbation series.

A novel time-dependent state in the form of traveling waves in electrohydrodynamic convection in a thin (15 μm) cell of very large aspect ratio is experimentally studied. The transition leading to uniform waves is a continuous one bifurcating directly from the homogeneous state. The onset of spatiotemporal turbulence in this 2D system is characterized by the appearance of topological defects. The number of defects increases with the control parameter, and their statistical distribution is in very good quantitative agreement with a theoretical curve recently derived for "topological turbulence."

We have measured the absorption of 1-ps laser pulses interacting with matter at intensities from ${10}^{10}$ to ${10}^{16}$ W/${\mathrm{cm}}^2$. The variations of absorption with incidence angle and polarization have been used to infer submicron plasma-density-gradient scale lengths. The results show a transition between a regime of laser interaction with sharply bounded dense cold matter ($I\le 5\times {10}^{12}$ W/${\mathrm{cm}}^2$), where absorption is by the usual skin depth effect, to a regime of interaction with a plasma of very steep density gradient ($\frac{L}{\lambda }\le 0.2$) ($5\times {10}^{12}\mathrm{W}/{\mathrm{cm}}^2\le I\le {10}^{15}\mathrm{W}/{\mathrm{cm}}^2$).

It has been found that the ${\mathrm{H}}^{-}$ output current from a multicusp source can be substantially increased if the hydrogen plasma is seeded with cesium or barium. Experimental results demonstrate that, for a pure-hydrogen discharge, the ${\mathrm{H}}^{-}$ ions extracted from a multicusp source are indeed produced in the plasma volume. However, if barium is mixed with hydrogen in the source discharge, the majority of the ${\mathrm{H}}^{-}$ ions are generated on the anode walls.

We present measurements of the Raman backscatter produced by laser-plasma interaction where the laser focal profile was smoothed by induced spatial incoherence (ISI). The Raman backscatter with the ISI beam is much smaller than that with an ordinary beam. The onset of Raman backscattering with ISI followed the predictions of a convective gain model to within 30% in intensity.

The time-dependent behavior of a magnetized, two-dimensional plasma-wall sheath has been studied through particle simulations, which have shown that the cross-field sheath develops into a turbulent boundary layer, driven by the Kelvin-Helmholtz instability. The sheath acquires an equilibrium thickness $l_x\sim 5{\rho }_i$, and maintains long-lived vortices, with amplitudes $\delta \phi \sim -\frac{2T_i}{e}$, which drift parallel to the wall at half the ion thermal velocity. A central simulation result is that for ${\omega }_{\mathrm{pi}}\ge 2{\omega }_{\mathrm{ci}}$, the anomalous particle transport in the sheath scales like Bohm diffusion.

The morphological growth dynamics of chemical vapor deposition is studied with a model that takes account of both diffusive transport in the bulk and the kinetics of surface reactions. For the case of a fixed flux of reactant species far from the surface, we study numerically the crossover from diffusion-limited growth to surface kinetic-limited growth. In the latter case, one can qualitatively account for the morphology at early and intermediate times by use of a nonlinear growth model which takes explicit account of the destabilizing influence of the bulk phase diffusion field.

The thermal conductivity $\kappa$ of epoxy resin, MY750, cured with the stoichiometric quantity and twice that quantity of ethylene diamine, has been measured in the range 2-110 K. Both specimens show a plateau in $\kappa$ in the liquid-helium region, and at higher temperatures $\kappa$ has an additional term which is proportional to the temperature. This is in accord with the model of Alexander, Entin-Wohlman, and Orbach [Phys. Rev. B 34, 2726 (1986)] for phonon-assisted fraction hopping above the plateau. The magnitude of this contribution, based on the theory of Jagannathan, Entin-Wohlman, and Orbach are in reasonable agreement with our experimental values.

A molecular-dynamics simulation of liquid arsenic shows good agreement with recent neutron-diffraction data. The coordination number and the average bond length and bond angle are very close to their values in rhombohedral As. This shows that the short-range order in liquid As is very close to that in the crystal. The experiment has been interpreted as representing the first evidence for the existence of a Peierls distortion in a liquid. Our results suggest that the structure could also be interpreted as arising from a modulation of the random packing of atoms by the Friedel oscillations in the effective interatomic interactions.