We present a model for slow-rollover inflation where the vacuum energy that drives inflation is of the order of ${\mathit{G}}_{\mathit{F}}^{\mathrm{-}2}$; unlike most models, the conversion of vacuum energy to radiation (‘‘reheating’’) is moderately efficient. The scalar field responsible for inflation is a standard-model singlet, develops a vacuum expectation value of 4×${10}^6$ GeV, has a mass of about 1 GeV, and can play a role in electroweak phenomena. We also discuss models where the energy scale of inflation is somewhat larger, but still well below the unification scale.

We present a graphical and statistical comparison of observations of solar neutrinos with theoretical predictions for the Mikheyev-Smirnov-Wolfenstein effect and a class of ‘‘nonstandard’’ solar ‘‘models.’’ The method used to compare the results makes the level of agreement or nonagreement between theory and observation more readily apparent. Included in our analysis are the standard-solar-model flux uncertainties. We also present predictions for Solar Neutrino Observatory charge-current rates.

We calculate properties of neutron star matter at subnuclear densities using an improved nuclear Hamiltonian. Nuclei disappear and the matter becomes uniform at a density of about 0.6${\mathit{n}}_{\mathit{s}}$, where ${\mathit{n}}_{\mathit{s}}$≊0.16 ${\mathrm{fm}}^{\mathrm{-}3}$ is the saturation density of nuclear matter. As a consequence, the mass of matter in the crusts of neutron stars is only about half as large as previously estimated. In about half of that crustal mass, nuclear matter occurs in shapes very different from the roughly spherical nuclei familiar at lower densities. The thinner crust and the unusual nuclear shapes have important consequences for theories of the rotational and thermal evolution of neutron stars, especially theories of glitches.

The production of the ${\mathrm{\chi }}_1$ and ${\mathrm{\chi }}_2$ states of charmonium has been observed in 300 GeV/c ${\mathrm{\pi }}^{\pm }$N and pN interactions. The fraction of the total inclusive J/ψ production due to radiative χ decay has been determined to be 0.40±0.04, 0.37±0.03, and 0.30±0.04 for the ${\mathrm{\pi }}^{+}$, ${\mathrm{\pi }}^{\mathrm{-}}$, and proton data, respectively. Total cross sections have been obtained of 131±18±14 and 188±30±21 nb/nucleon in the 300 GeV/c ${\mathrm{\pi }}^{\mathrm{-}}$N interactions for ${\mathrm{\chi }}_1$ and ${\mathrm{\chi }}_2$ production. By measuring the contributions to the J/ψ production due to both ψ’ and radiative χ decay, the cross sections for direct J/ψ production have been determined to be 97±14, 102±14, and 89±12 nb/nucleon for ${\mathrm{\pi }}^{+}$, ${\mathrm{\pi }}^{\mathrm{-}}$, and protons, respectively.

The electroproduction of neutral pions off protons close to threshold is studied within the framework of chiral perturbation theory. We compare to the recent data from NIKHEF and find good agreement. Further measurements as tests of chiral symmetry are discussed.

The curvature energy is shown to give a very significant contribution to the mass of strangelets. Assuming three massless quark flavors, the energy per baryon is increased by roughly (435 MeV) ${\mathit{A}}^{\mathrm{-}2/3}$ within the MIT bag model, dramatically destabilizing the experimentally accessible strangelets with low baryon number A.

We have searched for the effect of a neutrino of mass 17 keV/${\mathit{c}}^2$ in the beta decay of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ with an appartus incorporating a high-resolution solid-state detector and a superconducting solenoid. The experimental mixing probability, ${\sin }^2$θ=-0.0004±0.0008(stat) ±0.0008(syst), is consistent with zero, in disagreement with several previous experiments. Our sensitivity to neutrino mass is verified by measurements with a mixed source of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, which artificially produces a distortion in the beta spectrum similar to that expected from the massive neutrino.

In general, the spectrum of lepton pairs produced in nuclear reactions depends on both invariant mass and momentum. But under a few reasonable assumptions on the time evolution of the system, we show that once the quark-gluon plasma is created in ultrarelativistic heavy ion collisions, the observed dilepton spectrum between the φ and J/ψ peak becomes dependent essentially only on its transverse mass ${\mathit{M}}_{\mathit{T}}$ and thus shows ${\mathit{M}}_{\mathit{T}}$ scaling. This scaling will not be observed if the quark-gluon plasma is not created in collisions.

Valence correlation schemes provide powerful tools to interpret nuclear phenomenology. It is shown that nearly all B(E2:$2_1^{+}$→$0_1^{+}$) values from light nuclei to the actinides are encompassed in a tight correlation envelope by expressing these B(E2) values in Weisskopf units, normalizing to the mass, and plotting against ${\mathit{N}}_{\mathit{p}}$${\mathit{N}}_{\mathit{n}}$. ‘‘Deviant’’ nuclei are thereby highlighted, and it is concluded that B(E2:$2_1^{+}$→$0_1^{+}$) values alone can provide signatures, not only of quadrupole collectivity, but also of axial asymmetry, hexadecapole shapes, shape coexistence, saturation of collectivity, shell structure, and the evolution of shell gaps. Moreover, combined with E($4_1^{+}$)/E($2_1^{+}$) ratios, B(E2:$2_1^{+}$→$0_1^{+}$) values provide a simple new method to distinguish the two principal classes of nuclear phase transitions.

Electron energy spectra from ionization of the noble gases by 617-nm, 100-fs intense laser pulses show that the periodical double structure of narrow Stark-induced resonances and above-threshold ionization disappears gradually from xenon to helium. This implies that shifts and widths become of the order of the atomic-orbital frequencies, as expected at the onset of the tunneling regime.

We have observed the vibrational levels of rubidium atoms spatially confined in two dimensions by two crossed optical standing waves (oriented along the x and y axes) with mutually orthogonal linear polarization (in the x-y plane). When the two standing waves oscillate with a 90° time phase delay, the atoms are confined by dipole forces to the intensity maxima forming a two-dimensional collimated array of linear de Broglie waveguides, spaced by half an optical wavelength. When the standing waves oscillate in phase no vibrational energy structure can be observed.

We have measured the elastic collision cross section for spin polarized atomic cesium. Neutral cesium atoms are optically cooled, then loaded into a dc magnetic trap. We infer the scattering rate from the rate at which anisotropies in the initial energy distribution are observed to relax. The cross section for F=3, ${\mathit{m}}_{\mathit{F}}$=-3 on F=3, ${\mathit{m}}_{\mathit{F}}$=-3 is 1.5(4)×${10}^{\mathrm{-}12}$ ${\mathrm{cm}}^2$, and is independent of temperature from 30 to 250 μK. This determination clarifies the technical requirements for attaining Bose-Einstein condensation in a magnetically trapped Cs vapor. We also study heating due to glancing collisions with 300 K background Cs atoms.

We have measured the doubly differential energy and angular distribution of low-energy electrons emitted in collisions of ${\mathrm{H}}^{+}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{2+}{}_{}{}^{}$ on Ne at 106 keV/u. In this way, we are able to obtain information about the shape of the soft electron ionization peak. Against current belief, but in accordance with a two-Coulomb-center interaction of the emitted electron, we find it to be strongly asymmetric in the forward-backward direction. We discuss the shape of the cross section and introduce a parametric expression for fitting the data.

Dissociative recombination of ${\mathrm{HeH}}^{+}$ has been studied for the ${\mathrm{HeH}}^{+}$ ion stored in a storage ring. A strong recombination resonance having a peak at around 20 eV center-of-mass energy has been found for the first time in addition to the known recombination at around 0 eV center-of-mass energy. The strength of the recombination rate changes depending on the storage time of ${\mathrm{HeH}}^{+}$ ions.

The dissociative recombination cross section between ${\mathrm{HD}}^{+}$ molecules and electrons at energies between 0.3 and 40 eV has been measured for the first time in an ion storage ring. The ion beam, stored with a mean lifetime of ∼5 s, was observed to be vibrationally cold. In the measured cross section, theoretically predicted high-energy resonances appeared, which can be attributed to recombination via doubly excited Rydberg states of HD.

The cross section for neutral-channel dissociative recombination of vibrationally cooled ${\mathrm{H}}_3^{+}$ at energies between 0.0025 and 30 eV has been measured by utilizing the electron cooler at the storage ring CRYRING. The molecular ions were stored at an energy of 32.6 MeV and phase-space cooled by the electron cooler for about 8 s prior to data taking. A peak in the cross section at 9.4 eV is interpreted as a direct adiabatic neutral-channel recombination through the ${}_{}{}^2{}_{}{}^{}$${\mathit{A}}_1$ resonant state. The cross section below 1 eV is in rather good agreement with single-pass data.

Coherent and squeezed states for the time-dependent-frequency harmonic oscillator are analyzed using maximum entropy principle techniques. The information-theoretic procedure leads to results equivalent to that of the Wigner-function formalism, although the former gives a physical interpretation of the involved parameters and allows for a nonzero-temperature density matrix.

Quantum correlated twin beams have been generated using series and parallel coupled light emitting diodes. Furthermore, sub-Poissonian light, with a noise level 1.4 dB below the standard quatnum limit, has been measured in both circuits. From the parallel coupled setup it could be deduced that electrical partition noise may be made negligible.

The transport of a relativistic electron beam was studied experimentally and numerically in a magnetic field configuration which consists of a focusing wiggler as well as an additional axial guide field. A new beam divergence was found for the lower side of the magnetoresonance. It was identified as due to the effect of the second harmonic mode of the cyclotron frequency in the resonance, determined by n${\mathrm{\Omega }}_{\mathrm{\parallel }}$=${\mathit{k}}_{\mathit{w}}$${\nu }_{\mathrm{\parallel }}$ for n=2. The harmonic resonance was detected for the planar wiggler first, and it could appear also for the helical one.

Neutron diffraction measurements on a highly doped single crystal of ${\mathrm{La}}_2$${\mathrm{NiO}}_{4+\mathrm{\delta }}$ (δ=0.105) reveal that below room temperature the crystal undergoes phase separation into an orthorhombic structure, with a doubled unit cell along c, and a tetragonal phase. The lattice distortion in the orthorhombic phase suggests charge-density-wave order, and related diffuse scattering is observed at room temperature. The orthorhombic phase orders antiferromagnetically below 55 K with a significant ordered moment (∼0.7${\mathrm{\mu }}_{\mathit{B}}$).