A theoretical calculation for the electronic structure of an exciton bound to a nitrogen trap in GaP is presented. For the first time, the band-structure effect for both the electron and hole and their mutual Coulomb interaction are included simultanteously. It is found that the bare electron is bound by only 0.6 meV instead of 8 meV as usually quoted. Furthermore, this calculation predicts the $A-B$ splitting and the oscillator strength of the bound-exciton luminescence in good agreement with the experimental data.

The authors show that, contrary to the usual assumption, the local noise sources at two different points are not uncorrelated, but indeed are correlated over short distances, of the order of magnitude of a fraction of a micrometer. The two-point correlation function is expressed for hot carriers in semiconductors when randomizing scatterings are involved. The expression of the frequency-dependent diffusion coefficient for hot carriers is given as an explicit integral form involving the distribution function.

A compact hyperbolic three-manifold is substituted for the infinite space $H^3$, as space section of Friedmann's cosmological model of negative curvature. Some consequences are briefly analyzed. In particular it is shown that an apparent observational isotropy persists when the particle horizon intersects an anisotropic region of space.

The component formulation of the Wess-Zumino superspace action leads, when compared with the general results of Cremmer et al., to a nonminimal version of $N=1\mathrm{}$ supergravity. A new superpotential, $g_2\mathrm{}\left(z\right)\mathrm{}$, has been found that gives a scalar potential $V\left(z\right)\mathrm{}$ that is even in $z$ and which breaks supersymmetry inside the circle of radius $\frac{\sqrt{6}}{\kappa }$ in the complex $〈z〉$ plane.

Total magnetic flux trapped in a tiny toroidal magnet is measured by an electron holography technique to test predicted flux quantization. The experimental results show that the magnetic flux is quantized neither by $\frac{h}{e}$ units nor by $\frac{h}{2e}$ units. This fact provides further evidence for the existence of the Aharonov-Bohm effect.

The chaotic nature of "caviton turbulence" is studied in one-dimensional, many-Fourier-mode numerical simulations of the driven dissipative Zakharov equations. Above the modulational instability threshold the system evolves into a variety of stable patterns of cavitons which become chaotic for stronger driving. The cavitons remain coherent for times long compared to the shortest Lyapunov time.

The current state of theoretical understanding related to the question posed in the title is incomplete. This paper presents results of numerical experiments which are consistent with a positive answer. These results also bear on the problem of characterizing possible routes to chaos in nonlinear dynamical systems.

The energy dependence of the cross section for neutrino- and antineutrino-nucleon charged-current interactions has been determined from data taken in Fermilab's dichromatic neutrino beam. $\frac{{\sigma }^{\nu }}{E}=(0.669\mathrm{}\pm 0.003\pm 0.024)\times {10}^{-38\mathrm{}}$ ${\mathrm{cm}}^2$/GeV and $\frac{{\sigma }^{\overline{\nu }}}{E}=(0.340\mathrm{}\pm 0.003\pm 0.02)\times {10}^{-38\mathrm{}}$ ${\mathrm{cm}}^2$/GeV are found. These results are higher than some previous measurements.

The inclusive branching fraction for $B$-meson decay into $D^0$ mesons and the momentum spectrum of the $D^0$'s have been measured. $0.8\pm 0.2\pm 0.2 D^0$ per $B$ decay was found. The shape of the spectrum suggests an interesting picture of $B$-meson decay.

The derivation of kinetic equations for the classical and quantum (Wigner) distribution functions for a plasma with non-Abelian interactions is outlined. Particular emphasis is put on the relation between the color structures in the classical and the quantum theories.

A new test of the principle of detailed balance in the nuclear reactions ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}(p,{\alpha }_0){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}(\alpha ,p_0){}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ at bombarding energies $7.3 \mathrm{MeV}<~E_p<~7.7 \mathrm{MeV}$ and $10.1 \mathrm{MeV}<~E_{\alpha }<~10.5 \mathrm{MeV}$, respectively, is reported. Measured relative differential cross sections agree within the experimental uncertainty $\Delta =\pm 0.51\%$ and hence are consistent with time-reversal invariance. From this result an upper limit $\xi <~5\times {10}^{-4\mathrm{}}$ (80% confidence) is derived for a possible time-reversal-noninvariant amplitude in the reaction.

Hybrid values of the intrinsic gyromagnetic ratio and the absolute values of the decoupling parameters have been found for two sets of approximately degenerate opposite-parity bands with $K={\frac{3}{2}}^{\pm }$ and $K={\frac{1}{2}}^{\pm }$ in ${}_{}{}^{227}{}_{}{}^{}\mathrm{Ac}$, as would be expected for intrinsic parity mixing in the single-particle states due to octupole deformation. These properties are able to test quantitatively the change in the Nilsson wave functions resulting from octupole deformation.

An anomalous short mean free path for projectile fragments has been observed in emulsions. The effect disappears in the first few centimeters and it has been suggested that the disappearance is due to a lifetime effect. The projectile fragmentation yields from a solid and a dilute Cu target bombarded by 1.7-GeV/u ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ have been measured and it is concluded that the disappearance of the effect is not due to decay.

On the basis of the two-center shell model a molecular reaction theory is applied to the reaction ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$)${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$. Prominent structures in the measured differential cross sections can be reproduced by this theory.

Preliminary experimental results are reported for the deflection of Na atoms in an atomic beam by a transverse standing-wave laser field whose frequency is tuned between the two ground-state hyperfine components of the $D_2$ line. In contrast to the two experiments done previously, a splitting of the beam into two symmetric peaks whose separation increases with the electric-field is seen here. In addition, the data show evidence for atomic diffraction: a tendency for scattered atoms to acquire momentum in multiples of $2\hslash k$.

An inverted cusp in the near-zero-velocity electron-loss spectrum for a $2p \mathrm{}(m=0\mathrm{})\mathrm{}$ initial state is predicted for an attractive final-state Coulomb interaction. The dip occurs in the singly differential cross section $\frac{d\sigma }{d{v}_e}$, calculated in Born approximation, at $v_e=v_P$, where the electron velocity $v_e$ matches the projectile velocity $v_P$ and where the familiar cusp normally appears. The dip becomes more pronounced with increasing projectile velocities $v_P\to \infty$. Its existence is traced to the odd ${\Pi }_z$ parity of the initial state.

Attention is called to a laboratory experiment of an optical-fiber interferometer which can show the gravitationally induced phase shift of optical waves. A phase shift of ∼ ${10}^{-6\mathrm{}}$ rad is anticipated for the Earth's gravitational potential difference of 1 m when a He-Ne laser and two multiple-turn optical-fiber loops of length 5 km are used. The phase shift can be varied by rotating the loops about an axis parallel to the Earth's surface. This order of phase shifts can be detected by current optical-fiber interferometric techniques.

A simple one-dimensional nonlinear equation including effects of instability, dissipation, and dispersion is examined numerically. It is observed that for the strongly dispersive case the temporal evolution is characterized by formation of a row of solitary pulses of equal equilibrium amplitudes. The width of each pulse is determined by the relative importance of the growing and the damping effects. The equilibrium amplitude increases as the dispersive effect increases.

The number of photons emitted in a short time interval by a single atom in the process of resonance fluorescence is measured, and it is shown that the probability distribution of this number is sub-Poissonian.

The sloshing-ion density distribution is produced in one of the minimum-$B$ mirrors of GAMMA 6 by injection of neutral beams at 62° to the axis. The formation of sloshing ions is confirmed by pitch-angle distributions measured with secondary emission detector arrays and a gridded energy analyzer. A dip of plasma potential is observed associated with the density minimum of the sloshing-ion distribution.