We describe a new quantum nondemolition method to monitor the number N of photons in a microwave cavity. We propose coupling the field to a quasiresonant beam of Rydberg atoms and measuring the resulting phase shift of the atom wave function by the Ramsey separated-oscillatory-fields technique. The detection of a sequence of atoms reduces the field into a Fock state. With realistic Rydberg atom-cavity systems, small-photon-number states down to N=0 could be prepared and continuously monitored.

The q-deformations of the quantum harmonic oscillator are used for to describe the generalized Jaynes-Cummings model (JCM) by using the q-analog of the Holstein-Primakoff realization of the su(1,1). The corresponding dynamical symmetry is described by a quantum algebra. The q-analogs of the Barut-Girardello and the Perelomov coherent states are introduced and the expectation value of ${\mathrm{\sigma }}_3$ is calculated. The periodic revivals of the generalized JCM are destroyed for increasing deformation parameter q. The deformed original JCM in the rotating-wave approximation can be described by the u(1‖1${)}_{\mathit{q}}$, while its relaxation extends the dynamical algebra to the osp(2‖2${)}_{\mathit{q}}$ quantum superalgebra.

Conformational dynamics of donor-acceptor-modified molecular chains is examined within a tight-binding scheme in adiabatic approximation. The topology of Born-Oppenheimer hypersurfaces in configuration space is shown to control the possible structural changes. Irrespective of chain length, the photoinduced structural quantum dynamics can be mapped approximately onto an effective three-level system that is coupled to the light field and a bath and treated by a generalized master equation.

Argon photoion spectra have been obtained for the first time in coincidence with K-LL and K-LM Auger electrons, as a function of photon energy. The simplified charge distributions which result exhibit a much more pronounced photon-energy dependence than do the more complicated noncoincident spectra. In the near-K-threshold region, Rydberg shakeoff of np levels, populated by resonant excitation of K electrons, occurs with significant probability, as do double-Auger processes and recapture of the K photoelectron through postcollision interaction.

We consider a spherical system composed of N concentric fluid shells having perturbations of amplitude ${\mathrm{\eta }}_{\mathit{i}}$ at interface i, i=1,2,...,N-1. For arbitrary implosion-explosion histories ${\mathit{R}}_{\mathit{i}}$(t), we present the set of N-1 second-order differential equations describing the time evolution of the ${\mathrm{\eta }}_{\mathit{i}}$ which are coupled to the two adjacent ${\mathrm{\eta }}_{\mathit{i}\pm 1}$. We report analytical solutions for the N=2 and N=3 cases. We also present a model to describe the evolution of a turbulent mixing layer in spherical geometry when the interface between two fluids undergoes a constant acceleration or a shock.

The electron energy distribution function measured with improved energy resolution revealed a large number (≊90%) of low-energy electrons having an abnormally low electron temperature (T≊0.3 V) resulting in a considerably lower mean electron energy than found in all published probe measurements in argon rf discharges at 13.56 MHz. With increasing gas pressure an abrupt transition to a high-temperature mode was found. The low-temperature mode and the observed transition are attributed to a change from stochastic to collisional electron heating enhanced by the Ramsauer effect.

The standard solar model predicts that the Sun’s luminosity has increased by 40% over the past 5 Gyr of main-sequence burning, a result that has troubled geophysicists and paleoclimatologists. This increase is accompanied by an exponential growth in the ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrino flux, with a doubling time of 0.85 Gyr. I argue that one nuclear system exists that, in principle, could yield a quantitative terrestrial record of these past changes. It is not clear whether the reading of that record is within present experimental capabilities.

In non-Abelian lattice gauge theories, the Gauss’s-law constraint is solved, enabling gauge-invariant local dynamics. For the 2+1, SU(2) case, the result is a quantum theory of a discretized membrane. Further, this is equivalent to a theory of integer-valued scalars with derivative interactions and a ‘‘dual’’ gauge invariance. This is the dual form of 2+1, SU(2) gauge theory.

A finite-size test was carried out for the finite-temperature chiral phase transition in QCD for flavor number ${\mathit{N}}_{\mathit{f}}$=4 and 2 on a lattice with four time slices using the Kogut-Susskind quark action at quark mass of 0.025 in lattice units. All the evidence supports a first-order transition for ${\mathit{N}}_{\mathit{f}}$=4. For ${\mathit{N}}_{\mathit{f}}$=2, however, the data on spatial lattice up to ${12}^3$ fail to yield convincing finite-size signatures for a first-order transition at this quark mass.

A natural axion-free solution of the strong CP problem at tree level is noted within an E(6) grand unified theory. Using this as a springboard, it is shown that several flipped SU(5) theories which occur in superstring phenomenology contain within them a mechanism which enforces θ¯=0 at high accuracy.

Sum rules for quark and lepton masses are derived from the Ward identity of Chanowitz and Ellis for the vertex function of the trace of the energy-momentum tensor and two axial-vector currents, and the partially conserved axial-vector current hypothesis. The sum rules indicate, among other things, that the constituent masses of the u and d quarks and those of the techniquarks, if any, are about 300 MeV and 300 GeV, respectively.

We analyze the evolution of the flavor-changing electromagnetic vertex as a function of the external initial quark mass ${\mathit{m}}_{\mathit{e}}$, in the three-generation standard model. We find a substantial threshold enhancement in the vertex, to one-loop order, when ${\mathit{m}}_{\mathit{e}}$ is of the order of the mass of the W boson. We comment on QCD corrections.

We show how to sum arbitrarily complicated exchange contributions to baryon-baryon and meson-baryon scattering to leading order in 1/${\mathit{N}}_{\mathit{c}}$ (${\mathit{N}}_{\mathit{c}}$ being the number of colors). A semiclassical structure is obtained, in close correspondence to vector-meson-augmented Skyrme models.

The orthonormal-correlated-states method is used to study the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(e,e’p${)}^3$H reaction. The effects of short-range correlations, orthogonality corrections, p${+}^3$H interaction in the final states, and two-body charge and current operators bring the theoretical predictions into fair agreement with the NIKHEF and Saclay data.

The influence of the color van der Waals force in the elastic scattering of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at sub-barrier energies is studied. The conspicuous changes in the Mott oscillation found here are suggested as a possible experimental test.

The cross sections for massive residues from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${+}^{40}$Ca and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$${+}^{27}$Al collisions were calculated with an improved Boltzmann-Uehling-Uhlenbeck equation. The calculated residue cross sections decrease with incident energy, an effect which does not appear related to the residue excitation energy. Larger residue cross sections result from calculations with larger in-medium nucleon-nucleon cross sections or with equations of state which are less attractive at subnuclear density. This dual sensitivity may be eliminated by measurements of observables associated with the coincident light particles.

Breakup of 63-MeV and 42-MeV ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ near the α-t threshold is examined from the astrophysical point of view. A new approach is made to extract indirectly astrophysical S factors. The S factors are compared with those deduced from radiative-capture measurements. It is shown that the energy dependence favors the recent capture data of Schröder et al.

Mechanisms of parasitic wave excitation in a high-current Raman-regime free-electron laser (FEL) are investigated by use of a one-dimensional multimode FEL amplification code. It is found that multimode coupling among sideband waves and the primary wave plays an important role in the parasitic wave excitation in addition to the sideband instability. Such a multimode coupling process is observed in both the linear amplification stage and the nonlinear trapping stage, and modulates the output signal to a level comparable with that solely due to the sideband instability.

The linear theory of electromagnetic radiation from a backward-wave oscillator with a plasma-filled, sinusoidally corrugated waveguide driven by a relativistic electron beam has been derived and analyzed numerically. The presence of plasma can cause a substantial increase in the spatial growth rate of the absolute instability. For high plamsa densities, however, the absolute instability is suppressed and only the convective instability remains. The predicted radiation enhancement can be attributed to a decrease in the group velocity of the backward wave in the presence of a plasma.

It is shown by numerical simulations that in a collisionless plasma electron inertia leads to inefficient neutralization of positive space charge and allows large positive potentials (φ≫${\mathit{kT}}_{\mathit{e}}$/e) to be established and maintained on the time scale of ion motion. This is true even if the buildup of positive space charge is so slow that it corresponds to a small fraction of the random electron current of the surrounding plasma. A simple physical model clarifies the physics of the process and provides an analytical expression for the potential.