We investigate neutrino spin precession in primordial magnetic fields, taking previously ignored neutrino refractive effects into account. A present-day intergalactic field strength ${\mathrm{B}}_0$ implies that the magnetic dipole moments of any two neutrino species are bounded by ${\mathrm{\mu }}_{\nu }$≲${10}^{\mathrm{-}16}$${\mathrm{\mu }}_{\mathrm{B}}$[(${10}^{\mathrm{-}9}$ G)/${\mathit{B}}_0$] because of nucleosynthesis constraints on the number of neutrino flavors.

We propose and study a compactification of the heterotic string on an asymmetric orbifold that leads to a zero cosmological constant in four dimensions even when 〈W〉≠0.

Membrane field theory is defined as a theory of surface functionals which incorporates membrane dynamics in the Dirac form. The excitation spectrum depends on the topology of membranes. Solving the field equation exactly, we show that toroidal membrane theory in four dimensions contains massless particles and yields an equally spaced mass-squared spectrum.

It is argued that the zero-momentum two-point function in a finite box can be used to get ${\mathrm{f}}_{\mathrm{\pi }}$ in the linear σ model. The method is based on a soft-pion finite-size theorem which is conjectured to hold if the boundary conditions are periodic. The present procedure is expected to be much more efficient than a previous proposal.

We report on a search for the flavor-changing neutral-current decays $K_L^0$→μ+e and $K_L^0$→e+e. Limits obtained for these processes are B($K_L^0$→μ+e)<6.7×${10}^{\mathrm{-}9}$ and B($K_L^0$→e+e)<4.5×${10}^{\mathrm{-}9}$ (90% confidence level).

We report on a Dalitz-plot analysis of 250 ${\mathit{D}}^{\pm }$ and 290 ${\mathit{D}}_{\mathit{s}}^{\pm }$ decays into ${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{-}}$${\mathrm{\pi }}^{\pm }$. We measure the relative rate for each charmed meson decaying into φ${\mathrm{\pi }}^{\pm }$, K¯${\mathrm{*}}^0$(K${\mathrm{*}}^0$)${\mathit{K}}^{\pm }$, and nonresonant ${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{-}}$${\mathrm{\pi }}^{\pm }$, and determine the ${\mathit{D}}_{\mathit{s}}^{\pm }$ mass. In addition, we measure the relative branching ratios for the decays of ${\mathit{D}}_{\mathit{s}}^{\pm }$ and ${\mathit{D}}^{\pm }$ into φ${\mathrm{\pi }}^{+}$${\mathrm{\pi }}^{\mathrm{-}}$${\mathrm{\pi }}^{\pm }$ and nonresonant ${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{-}}$${\mathrm{\pi }}^{+}$${\mathrm{\pi }}^{\mathrm{-}}$${\mathrm{\pi }}^{\pm }$.

Spin-correlation parameters $A_{\mathrm{LL}}$, $A_{\mathrm{SL}}$, $A_{\mathrm{NL}}$, $A_{N0}$, $A_{S0}$, $A_{L0}$, and $A_{0L}$ have been measured for the reaction pp→np${\pi }^{+}$ at 492, 576, 643, 729, and 796 MeV. An isobar analysis determines magnitudes and phases of partial waves up to NN ${}_{}{}^3{}_{}{}^{}F_3^{}{}_{}{}^{}$. For the amplitude NN${(}^1$$D_2$)→NΔ${(}^5$$S_2$), the phase shows a strong threshold enhancement in the NΔ channel, dropping from 44.4°±4.4° at 492 MeV to 11.9°±1.9° at 796 MeV. Other phases show little activity. Broad dibaryons are conclusively ruled out in ${}_{}{}^1{}_{}{}^{}\mathrm{D}_2^{}{}_{}{}^{}$, ${}_{}{}^3{}_{}{}^{}\mathrm{F}_3^{}{}_{}{}^{}$, and ${}_{}{}^3{}_{}{}^{}\mathrm{P}_2^{}{}_{}{}^{}$ in this energy range.

Transverse form factors have been measured for elastic electron scattering from ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, as well as for the electroexcitation of the 1.74-MeV ($J^{\pi }$=$O^{+}$, T=1) and 5.17-MeV ($2^{+}$, 1) levels of ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$. These results were utilized to determine the radial shape of the 1$p_{3/2}$ single-particle wave function within the nuclear interior.

The Schwinger representation of the SO(8) fermion-pair algebra in terms of d and quasispin vector s bosons is used in derivation of a microscopic boson coherent state having both particle-hole and pair excitations. The coherent state is the exact boson image of the Hartree-Fock-Bogolyubov variational solution. One can go beyond the mean field and introduce an intrinsic Hamiltonian having the boson condensate as an eigenstate.

We have investigated electron capture accompanied by nuclear scattering by studying the probability for electron capture from ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ in the vicinity of the 1.510-MeV elastic nuclear resonance ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$(p,p${)}^{22}$Ne. We have found a large nuclear resonance effect in the probability for electron capture. The data are in some disagreement with theoretical calculations by Jakubassa-Amundsen and Amundsen, based on the strong-potential Born approximation for electron capture.

The vibrational autoionization process of the ${\mathrm{Na}}_2$ nd Rydberg states has been studied in the presence of an electric field. The autoionization lifetime is shown to increase as a function of the electric field. This effect is interpreted in terms of Stark mixing with the high–angular-momentum hydrogenic complex. Moreover, it is shown that the autoionization lifetime grows with the field even in the inter-n-mixing region.

We predict a completely new behavior of fluorescence for large- or intermediate-size molecules which are highly isolated (e.g., in the interstellar medium). After a uv absorption, the energy decay by ir-emission alone is very slow (≃3 s). The system evolves at constant energy during a long time period in its phase space, and unusual phenomena can occur. We infer an inverse internal conversion and a resulting recurrent fluorescence that we propose to name Poincaré fluorescence. Such a behavior seems quite universal and has characteristics markedly different from the usual fluorescence.

We have studied the detailed energy balance in collisions of 10-MeV ${\mathrm{C}}^{6+}$ ions with Ne. In these collisions, the Ne is multiply ionized and the C ion may emerge as either ${\mathrm{C}}^{6+}$ or ${\mathrm{C}}^{5+}$. Projectile energy loss and scattering angle for a given carbon-ion charge state were determined in a high-resolution magnetic spectrograph and were measured in coincidence with the formation of a given Ne recoil-ion charge state. The amount of energy transferred to the continuum electrons exceeds, by far, the sum of the values of the ionization potentials.

The principles of a new high-energy photon source, ‘‘free positronium radiation,’’ are presented. It enables us to generate tunable monochromatic photon beams with energies of 2γ$m_0$$c^2$ and (${\alpha }^2$/2)γ$m_0$$c^2$. These radiations cover a broad energy range of photons from 0.1 keV to 10 GeV.

The local carbon particle diffusion coefficient was measured in the Proto S-1/C spheromak with use of a test-particle injection scheme. When the plasma was not in a force-free Taylor state, and when there were pressure gradients in the plasma, the particle diffusion was 5 times that predicted by Bohm and was consistent with collisional drift-wave diffusion. The diffusion appears to be driven by correlations of the fluctuating electric field and density. During the decay of the discharge when the plasma was in the Taylor state, the diffusion coefficient of the carbon was classical.

Stable and reproducible superconductivity has been unambiguously observed in a new Tl-Ba-Cu-O system containing no group-IIIB elements. Resistance in these rare-earth–free oxides starts to drop sharply above 90 K and reaches zero at 81 K. Meissner flux expulsion and diamagnetic shielding show bulk superconductivity. Further substitutions of elements for this system may lead to even higher-temperature superconductors.

Stable superconductivity up to 114 K has been reproducibly detected in Bi-Al-Ca-Sr-Cu-O multiphase systems without any rare-earth elements. Pressure has only a slight positive effect on ${\mathrm{T}}_{\mathrm{c}}$. These observations provide an extra material base for the study of the mechanism of high-temperature superconductivity and also the prospect of reduced material cost for future applications of superconductivity.

A new approach to the theory of high-temperature superconductivity is proposed, based on the two-dimensional antiferromagnetic spin correlations observed in these materials over distances large compared to the lattice spacing. The spin ordering produces an electronic pseudogap ${\Delta }_{\mathrm{SDW}}$ which is locally suppressed by the addition of a hole. This suppression forms a bag inside which the hole is self-consistently trapped. Two holes are attracted by sharing a common bag. The resulting pairing interaction $V_{k\mathrm{-}k\mathcal{’}}$ leads to a superconducting energy gap ${\Delta }_{\mathrm{SC}}$ which is nodeless over the Fermi surface, where ${\Delta }_{\mathrm{SC}\mathrm{\simeq }{\Delta }_{\mathrm{SDW}\exp (\mathrm{-}\mathit{t}/\mathit{\alpha }\mathit{U}}}$), with α of order unity.

Solid targets of ${\mathrm{SiO}}_2$ CsI, and organic layers of phenylalanine have been bombarded by multicharged ${\mathrm{Ar}}^{\mathrm{q}+}$ ions with 1≤q≤11. The secondary ion yield has been measured as a function of the incident charge state. No charge-state dependence was observed for most of the atomic and molecular ions, which were identified by time-of-flight mass spectrometry. In contrast, the ${\mathrm{H}}^{+}$-ion emission is strongly dependent on the incident charge state.

We report emission spectra and core hole lifetime for rare-gas and alkali-metal impurities in alkali-metal host lattices. The results lead to new proposed explanations for the anomalous core absorption edges reported in earlier work.