Axion emission from SN1987A by nucleon-nucleon axion bremsstrahlung is considered. On the basis of the neutrino observations the axion luminosity must be ≲${10}^{53}$ erg ${\mathrm{s}}^{\mathrm{-}1}$. This occurs if (1) axions couple very weakly: $m_a$≲0.75×${10}^{\mathrm{-}3}$ eV; or (2) axions couple strongly enough to be ‘‘trapped’’ and radiated from an ‘‘axion sphere’’ with $T_a$≲8 MeV: $m_a$≳2.2 eV. In general, ‘‘axion trapping’’ occurs for $m_a$≳0.016 eV. Our mass constraints are at best reliable to within a factor of ≃3.

We have performed an Eötvös-type experiment at a site with a significant slope in the terrain. For an intermediate-range force coupled to baryon number (N+Z) we find the product of strength ${\alpha }_0$ and range λ to be ${\alpha }_0$λ=-0.04±0.07 m for 25<λ<400 m. At greater ranges the value and the error increase linearly to ${\alpha }_0$λ=-0.05±0.09 m at 1.6 km. If the coupling is quark-flavor dependent, i.e., is purely to N-Z, we find, to well within the error, the same values for ${\alpha }_0$λ.

The (3+1)-dimensional SU(2) lattice gauge theory at finite temperature is studied by Monte Carlo renormalization-group methods on a ${32}^3$×${\mathrm{N}}_{\mathrm{t}}$ lattice with ${\mathrm{N}}_{\mathrm{t}}$=2 and 4. It is shown that the effective theory of the Polyakov loop has only short-range couplings and that the deconfining phase transition is governed by the same fixed point and critical indices as the three-dimensional Ising model, thus proving that the two theories belong to the same universality class.

We study the mixing of the $0^{++}$ glueball with a meson of the same quantum numbers in the framework of lattice QCD. The effects of dynamical quarks of bare mass ma=0.1 are taken into account by the pseudofermoin method. When confronted with a simple two-state mixing model our data are best interpreted as showing no evidence for mixing at the relatively large bare mass used.

The ‘‘universal seesaw mechanism,’’ which accounts for ${\mathrm{m}}_{\mathrm{e}}$,u,d≪${\mathrm{m}}_{\mathrm{W}}$, predicts ${\mathrm{m}}_{{\nu }_{\mathrm{L}}{\mathrm{m}}_{{\nu }_{\mathrm{R}}\mathrm{\approxeq }{\mathrm{m}}_{\mathrm{e}}^2}}$. Combined with an axial-vector symmetry principle, this mechanism allows for the coeexistence of heavy (≲${\mathrm{m}}_{\mathrm{W}}$) families without appeal to a hierarchy in Yukawa couplings and without introduction of additional mass scales. It then follows that (i) the physical right-handed heavy (light) ordinary fermions are mostly SU(2${)}_{\mathrm{R}}$ singlets (doublets), (ii) there is no analogous neutrino mass hierarchy, and (iii) ${\mathrm{m}}_{\mathrm{PQ}{\mathrm{m}}_{{\nu }_{\mathrm{L}}\mathrm{\approxeq }{\mathrm{m}}_{\mathrm{W}}^2}}$ sets the Peccei-Quinn mass scale.

The current experimental lower limit on proton lifetime from the decay mode p→ν¯+$K^{+}$ is used to obtain a limit on the intermediate mass scale in superstring-inspired models with rank-six groups. It is shown that the intermediate mass scale breaking in these models can be as low as 1×${10}^{14}$ GeV without violating current proton-decay data, provided the Yukawa couplings of superstring models are no larger than the corresponding couplings in SU(5) supergravity models. Scalar-quark masses are then larger than 1 TeV and the photino mass is no more than a few gigaelectronvolts.

We report the first experimental study of the angular momentum states populated by double-capture collisions of multiply charged ions. High-resolution spectra of L-Coster-Kronig electrons originating from ${\mathrm{O}}^{4+}$ 1$s^2$2pnl (n=6,7) states produced in 30–105-kev ${\mathrm{O}}^{6+}$+He collisions were obtained. Analysis of the observed spectra, performed with use of Hartree-Fock transition energies, indicates population of high–angular-momentum states. A classical-model calculation suggests that the correlated transitions producing the 1$s^2$2pnl autoionizing states involve both energy and angular momentum exchange between the two transferred electrons.

Pulsed free-electron lasers in which there is a dependence of the electron energy on the time of injection into the wiggler are expected to produce wide bandwidth but coherent chirped optical pulses with unique characteristics. Such pulses could be compressed in a dispersive medium to lengths on the order of a few optical periods. Chirping should also produce enhanced efficiency in the high-power trapped-particle regime.

A quantum mechanical analysis of a two-level atom in a coherently driven optical cavity is shown to predict steady-state atomic population inversion. Semi-classically this is forbidden because of the factorization of operator-product expectation values. The full quantum theory is much richer and different field states may be correlated with different atomic states. One consequence is that damping of the cavity field allows atomic polarization to be transferred from higher to lower field states and thus steady-state inversion becomes possible.

Previous studies have shown that the possible utility of the two-photon laser as a squeezed-state generator is negated by spontaneous-emission fluctuations. We here show that a two-photon correlated–spontaneous-emission laser can produce light which is both squeezed and free from spontaneous-emission fluctuations.

We compare the nonclassical states of light produced by a parametric oscillator for quantum noise of different strengths. Increasing noise strength brings a transition from a slightly perturbed classical state showing squeezing to a superposition of coherent states. We use the positive-P representation to illustrate the roles of quantum noise, quantum coherence, nonlinearity, and dissipation in this simple quantum dynamical system.

Statistical properties of solutions of the random-force–driven Burgers equation are investigated by use of the dynamic renormalization group and direct numerical simulations. The agreement between computed and analytical results on both exponents and amplitudes of the correlation functions is good. It is shown that a small-scale noise dominates large-scale, long-time (k→0,ω→0) behavior of the system and, as a consequence, no microscopic system of interacting particles described by Burgers equation in the hydrodynamic limit (k→0,ω→0) exists.

A concrete example is given which shows that the one-dimensional Ising and Gaussian model universality classes do not exhaust the universality classes of the one-dimensional continuous-spin Ising model. Thus the normal universality hypothesis fails in this simple, readily analyzable model.

Neutron and low-energy electron diffraction at 2≤T≤5 K are used to determine the structure of three incommensurate (IC) solid phases for ${\mathrm{D}}_2$ on graphite. The α phase is a uniaxial IC solid phase with striped domain walls due to strong substrate-induced modulation of the nearest-neighbor spacing. The γ phase is a rotated triangular IC phase with satellite diffraction peaks due to modulation intermediate between that of the α phase and the Novaco-McTague rotated IC phase which exists at higher density.

We report measurements of the osmotic susceptibility χ and long-range correlation length ξ of binary mixtures of the nonionic surfactant n-dodecyl octaoxyethylene glycol monoether with ${\mathrm{H}}_2$O and ${\mathrm{D}}_2$O, near the lower consolute temperature. Regardless of which solvent is used, we find 3D-Ising exponent values for both γ and ν, the exponents which describe the divergences of χ and ξ, respectively.

Small, two-dimensional islands of silver and gold formed in situ by evaporation onto graphite cleaved in ultrahigh vacuum are imaged atom by atom with a scanning tunneling microscope. These islands contain ordered regions of roughly 50 atoms in rectangular lattices, incommensurate with the substrate lattice, that are not close packed as in the bulk fcc structure. In one series of images, the shorter lattice spacing remained constant at 2.35±0.15 Å whereas the longer decreased from 4.05±0.1 to 3.5±0.1 Å over a period of roughly 10 min.

The heat capacity of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ adsorbed on a silver-powder substrate has been measured for temperatures between 0.4 and 7 mK and for coverages up to 5 atomic layers. The data show several features in common with those obtained for the ${}_{}{}^3{}_{}{}^{}\mathrm{graphite}$ system, including an anomaly in the exchange contribution to the heat capacity near 2.5 layers. In the graphite-substrate experiments the ferromagnetic anomaly is associated with the freezing of the second ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ layer. The second layer on the silver substrate, however, is found not to solidify.

We discuss modulated phases that can occur in thin liquid-crystal films composed of tilted, chiral molecules. While the phase diagram depends on all orders of a Landau expansion we find that either a striped phase of parallel defect walls or a lattice of hexagonal unit cells containing disclinations and bounded by intersecting walls can occur. The striped phase can occur with either a positive or negative bend elastic constant depending on the underlying microscopic parameters. The transition into the modulated phase is, in general, continuous with infinite defect separation at the transition.

Interference effects have been observed when coherently coupled x-ray beams are inelastically scattered by phonons in a crystal. The coherently coupled beams are prepared by using dynamical diffraction methods. This principle was applied to determine the phases of the phonon eigenvectors in silicon by an analysis of the intensity of the inelastically scattered x rays.

X-ray-absorption fine-structure measurements were made on pure Pb and dilute solid solutions of Hg in Pb. These measurements are consistent with a model of local premelting of bonds around the Hg impurities beginning around 400 K, which is 180 °C below the bulk melting temperature of the alloy. The results imply that initiation of bulk three-dimensional melting may occur around point defects, even for pure materials.