Using a formalism developed by Polychronakos, we explicitly construct a set of invariants of the motion for the Haldane-Shastry SU(N) chain.

We present a new lattice integrable system in one dimension of the Haldane-Shastry type. It consists of spins positioned at the static equilibrium positions of particles in a corresponding classical Calogero system and interacting through an exchange term with strength inversely proportional to the square of their distance. We achieve this by viewing the Haldane-Shastry system as a high-interaction limit of the Sutherland system of particles with internal degrees of freedom and identifying the same limit in a corresponding Calogero system. The commuting integrals of motion of this system are found using the exchange operator formalism.

We report on calorimetric measurements of the organic spin-density wave (SDW) conductor (TMTSF${)}_2$${\mathrm{PF}}_6$. The experiments were carried out from 8 to 20 K, with emphasis on the neighborhood of the 12.1 K SDW transition. The transition anomaly was less than 1% of the total specific heat at that temperature, and deviates substantially from the shape expected for mean-field theory for temperatures approximately 0.15 K on either side of the transition. A comparison to the thermodynamics of the 2D Heisenberg antiferromagnet is made.

Dynamic scaling of magnetic hysteresis in a few monolayer thick Fe/Au(001) films was studied by using surface magneto-optic Kerr effect. For low values of the frequency (Ω) and amplitude (${\mathit{H}}_0$) of an applied magnetic field, the hysteresis loss scales as A∝${\mathit{H}}_0^{\mathrm{\alpha }}$${\mathrm{\Omega }}^{\mathrm{\beta }}$ with α=0.59±0.07 and β=0.31±0.05. Our results confirm a recently proposed scaling law. The exponents are consistent with recent numerical simulations of the hysteresis of 2D Ising spins and suggest that the hysteresis dynamics in ultrathin ferromagnetic films belong to a dynamic Ising universality class.

The ac susceptibility in the two-dimensional Ising spin glass ${\mathrm{Rb}}_2$${\mathrm{Cu}}_{0.67}$${\mathrm{Co}}_{0.33}$${\mathrm{F}}_4$ and the two-dimensional random-exchange Ising ferromagnet ${\mathrm{Rb}}_2$${\mathrm{Cu}}_{0.89}$${\mathrm{Co}}_{0.11}$${\mathrm{F}}_4$ is observed to relax towards equilibrium on a time scale of hours following fast quenching to 3.9 K. Scaling of the in-phase and out-of-phase susceptibilities yields that the ordered domains grow according to (lnt${)}^{1/\mathrm{\psi }}$, with t expressed in units of a microscopic time, and ψ=1.07±0.10 and 0.20±0.05, respectively. Both values are in agreement with recent theoretical results and numerical simulations.

We report on the first observation of the twofold rotational anisotropy of second-harmonic generation (SHG) in the reflected light from a noncentrosymmetric crystal surface of GaAs(001). We interpret this as meaning that the interference of surface SHG and dipole-allowed bulk SHG having fourfold symmetry results in twofold anisotropy. The degree of anisotropy changes according to the surface reconstruction.

With atomic-force microscopy we studied etch pits in muscovite mica that was irradiated with 200-keV Ag ions and with recoiling daughter atoms emitted in alpha decay. Etching occurs by initiation of 1-nm-high steps at the point of intersection of an ion’s trajectory with the basal plane and by their subsequent spreading. Along some crystallographic directions in the basal plane, steps are observed to be paired, with a height of 2 nm; in other directions they remain separate. Possible future applications include alpha-recoil geochronology and searches for hypothetical dark-matter particles.

In analogy to current fluctuations found in solid state electronic microstructure devices, excess noise generated by the reversible ionization of sites in a transmembrane ionic channel was observed. By analyzing the pH-dependent fluctuations in the current through fully open single channels formed by the α-toxin protein, we were able to evaluate the protonation rate constants, the number of sites participating in the protonation process, and the effect of recharging a single site on the channel conductance.

The vacuum effective potential of three-dimensional SU(2) lattice gauge theory in an applied color-magnetic field is computed over a wide range of field strengths. The background field is induced by an external current, as in continuum field theory. Scaling and finite volume effects are analyzed systematically. The first evidence from lattice simulations is obtained of the existence of a nontrivial minimum in the effective potential. This supports a ‘‘ferromagnetic’’ picture of gluon condensation, proposed by Savvidy on the basis of a one-loop calculation in (3+1)-dimensional QCD.

A measurement of the lifetime of the charmed strange baryon ${\mathrm{\Xi }}_{\mathit{c}}^0$ is presented. The data were accumulated by the Fermilab high energy photoproduction experiment E687. The measurement has been made using 42±10 ${\mathrm{\Xi }}_{\mathit{c}}^0$→${\mathrm{\Xi }}^{\mathrm{-}}$${\mathrm{\pi }}^{+}$ decays. The lifetime of the ${\mathrm{\Xi }}_{\mathit{c}}^0$ is measured to be 0.${101}_{\mathrm{-}0.017}^{+0.025\mathrm{}}$±0.005 ps and its mass is measured to be 2462.1±3.1±1.4 MeV/${\mathit{c}}^2$.

We show that the differences between the Plastic Ball and DIOGENE experiments on sideward flow make it possible to asses independently, within the transport description of collisions, the effect of density dependence and momentum dependence of the nucleon optical potential. We estimate that the nuclear compressibility K lies between 180 and 235 MeV.

The spectrum of low energy beta-delayed alpha-particle emission of ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ was measured with high sensitivity; e.g., at ${\mathit{E}}_{\mathrm{\alpha }}^{\mathit{L}}$≊1 MeV, a sensitivity for a beta-decay branching ratio in the range of ${10}^{\mathrm{-}9}$ (to ${10}^{\mathrm{-}10}$) was achieved. We used previous theoretical work of Ji, Filippone, Humblet, and Koonin to extract from these data the astrophysical p-wave S factor for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ (α,γ${)}^{16}$O capture reaction, and find ${\mathit{S}}_{\mathit{E}1}$(300)=95±6(stat)±28(syst) keV b. This result is crucial, for example, for understanding the last stages of a massive star before a supernova.

The mass distributions from the sequential decay of the compound nuclei formed by the ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$${+}^9$Be and ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$${+}^{10}$B reactions at ${\mathit{E}}_{\mathrm{lab}}$≃11A MeV show no evidence of nuclear structure effects. We thus conclude that hot composite systems as light as ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ can behave like liquid droplets with no remnant shell effects.

We observe a new resonance structure in the associative ionization spectrum of laser-cooled sodium due to the collision of two atoms in different ground hyperfine states. This associative ionization is due to doubly resonant excitation at moderate internuclear separation through intermediate molecular states. Substructure within this resonance is evidence for the role of molecular bound states in this process. We present calculations modeling the effect of ground-state hyperfine structure, the importance of which was unanticipated in earlier theoretical studies.

We present results of the electronic structure and stability of some forty valence electron icosahedral ${\mathrm{Al}}_{12}$X (X=B, Al, Ga, C, Si, Ge, Ti, and As) clusters within the local spin density functional theory. It is shown that the stability of the ${\mathrm{Al}}_{13}$ cluster can be substantially enhanced by proper doping. For neutral clusters, substitution of C at the center of the icosahedron leads to the largest gain in energy. However, ${\mathrm{Al}}_{12}$${\mathrm{B}}^{\mathrm{-}}$ is the most strongly bound in this family. These results are in agreement with the recent experiments which also find ${\mathrm{Al}}_{12}$${\mathrm{B}}^{\mathrm{-}}$ to be highly abundant.

We analyze the propagation of a short intense laser pulse in underdense cold plasma. When no electron cavitation is present, a global invariant H is obtained, and its relation with self-focusing is studied. For relativistic self-focusing, H<0 is a sufficient and necessary condition. For relativistic and ponderomotive self-focusing, H<0 is sufficient but not necessary. Numerical simulations are performed to confirm the above points.

In W 7-AS the H mode has been observed for the first time in a currentless stellarator plasma. H modes are achieved with 0.4 MW electron cyclotron resonance heating at 140 GHz at high density. The H phases display all characteristics known from tokamak H modes including edge localized modes (ELMs). The achievement of the H mode in a shear-free stellarator without toroidal current has consequences on H-mode transition and ELM theories.

The long-wavelength hydrodynamics of the Renn-Lubensky twist grain boundary phase with grain boundary angle 2πα, α irrational, is studied. We find three propagating sound modes, with two of the three sound speeds vanishing for propagation orthogonal to the grains, and one vanishing for propagation parallel to the grains as well. In addition, we find that the viscosities ${\mathrm{\eta }}_1$, ${\mathrm{\eta }}_2$, ${\mathrm{\eta }}_4$, and ${\mathrm{\eta }}_5$ diverge like 1/‖ω‖ as frequency ω→0, with the divergent parts Δ${\mathrm{\eta }}_{\mathit{i}}$ satisfying Δ${\mathrm{\eta }}_1$Δ${\mathrm{\eta }}_4$=(Δ${\mathrm{\eta }}_5$${)}^2$, exactly. Our results should also apply to the predicted decoupled lamellar phase.

Random tiling models cover the plane with a set of rigid tiles without gaps between tiles and without overlap. This paper considers tilings of the plane by squares and equilateral triangles which display twelvefold rotational symmetry and quasi-long-range quasiperiodic translational order. Tiling configurations may be described as networks of interacting domain walls, for which the Bethe ansatz provides the exact (formal) partition function. Numerical evaluation yields the entropy and phason elastic constants with high accuracy.

We present molecular dynamics computer simulations of heat spikes similar to those appearing in high energy collision cascades. We determine characteristics of the thermal transport and, by changing the energy density and the initial temperature of the substratum, we study the solid-to-liquid transition of the core of the spike. The change in volume associated with this transition generates a narrow density wave that drives the material to strains above the theoretical shear strength of a perfect crystal, becoming in this way a new possible mechanism of collective generation of dislocation loops.