It is argued that the ratio $\frac{\Gamma ({\left(\overline{Q}Q\right)}^{\prime }\to (\overline{Q}Q\left)\eta \right)}{\Gamma ({\left(\overline{Q}Q\right)}^{\prime }\to (\overline{Q}Q\left)\pi \pi \right)}$ of hadronic transition rates between heavy quarkonium states is calculable within quantum chromodynamics in terms of triangle anomalies in the divergence of the axial current and in the trace of the energy-momentum tensor. In the case of transitions between ${\psi }^{\prime }$ and $\frac{J}{\psi }$ the present analysis is consistent with the data. More reliable test can be provided by experimental study of the transitions between ${\Upsilon }^{\prime \prime }$ and $\Upsilon$.

This Letter considers a second class of neutrino oscillations which can arise when both Majorana and Dirac neutrino mass terms exist. These oscillations mix neutrino members of weak current doublets with singlets of the same chirality. A depletion of a neutrino beam results, with apparent nonconservation of probability. Possible relevance to current oscillation experiments is discussed.

Differences in the kinetic energies of the fragments produced in the scission of the pairs of similar composite nuclei ${}_{}{}^{59}{}_{}{}^{}\mathrm{Cu}$-${}_{}{}^{60}{}_{}{}^{}\mathrm{Zn}$ and ${}_{}{}^{83}{}_{}{}^{}\mathrm{Y}$-${}_{}{}^{88}{}_{}{}^{}\mathrm{Zr}$ are interpreted as resulting from angular momentum fractionation. The energies indicate that some partial waves with angular momenta $10\hslash$ to $15\hslash$ below the sharp-cutoff fusion limit lead to strongly damped collisions.

Neutron spectra from the reaction ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$($p$,$n$) ${}_{}{}^{48}{}_{}{}^{}\mathrm{Sc}$ at 160 MeV reveal a prominent narrow peak at $E_x=16.8\mathrm{}$ MeV. This state is interpreted as a spin-flip isovector giant resonance; it carries a significant fraction of the $T_{>}$ ($T=4\mathrm{}$) Gamow-Teller strength. The observed position of this resonance agrees with both a recent shell-model prediction and with the position expected from systematics for the analog of the giant $M1\mathrm{}$ resonance in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$.

Atomic-excitation effects arising from sudden nuclear recoil are shown to be a significant factor in broadening the 14.23-MeV resonance in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$($p$,$p$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ measured with a high—energy-resolution polarized beam. The total width of the resonance is found to be 1010 ±30 eV.

Momentum spectra of protons in the reaction of $\gamma +\mathrm{Be}\to p$ + anything in the incident energy range from 180 to 420 MeV were measured. The spectrum obtained shows two peaks which are interpreted to be due to the protons in reactions $\gamma +``N\text{'}\text{'}\to p+\pi$ and $\gamma +``d\text{'}\text{'}\to p+n$, where $``N\text{'}\text{'}$ and $``d\text{'}\text{'}$ are the quasifree nucleons and neutron-proton systems, respectively, in the beryllium nucleus.

It is theoretically shown that the transmitted light from a ring cavity containing a nonlinear dielectric medium undergoes transition from a stationary state to periodic and nonperiodic states, when the intensity of the incident light is increased. The nonperiodic state is characterized by a chaotic variation of the light intensity and associated broadband noise in the power spectrum. The experimental possibility of observing such a transition is also discussed.

It is shown how the existence of low-dimensional chaotic dynamical systems describing turbulent fluid flow might be determined experimentally. Techniques are outlined for reconstructing phase-space pictures from the observation of a single coordinate of any dissipative dynamical system, and for determining the dimensionality of the system's attractor. These techniques are applied to a well-known simple three-dimensional chaotic dynamical system.

It is observed that the waves launched from a phased array antenna of four waveguides couple effectively with electrons under the condition of $\frac{{\omega }_0}{{\omega }_{1h}\mathrm{}\left(0\right)\mathrm{}}\gtrsim 2.0$. This coupling generates a rf-driven current, rather than heating of the bulk electrons, and the current/rf-power ratio of 110 A/kW was obtained with a rf power of 125 kW radiated into a plasma which included appreciable suprathermal electrons.

Preferential heating of electrons traveling in one direction can support a current even in the absence of a dc electric field. An immediate implication is that even waves which carry little toriodal momentum, such as electron cyclotron waves, may be attractive as a means for generating steady-state toroidal current in a tokamak. An analytical expression is derived for the current generated per power dissipated, which agrees remarkably well with numerical calculations.

Systematic red shifts for the Paschen $\alpha$, $\beta$, and $\gamma$ lines ($n=4,5,6\mathrm{}\to n=3\mathrm{}$) of He II are observed over an electron density range of (1-8)×${10}^{22}$ ${\mathrm{m}}^{-3\mathrm{}}$. The measurements are compared with combined estimates for plasma polarization and ion quadrupole effects. It is demonstrated that previous theoretical estimates have left out an important contribution to the polarization shift, which we estimate using the Debye model.

The phase diagram of liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixtures in the vicinity of the tricritical point has been determined at saturated vapor pressure and at 22.6 bars, close to solidification. Neither the critical exponent $\beta$ nor the slopes of the phase-separation curve change with pressure indicating universal behavior of the tricritical ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ system.

The critical dynamics of KMn${\mathrm{F}}_3$ above the cubic-tetragonal transition were studied by ultrasonics, including a novel phonon-echo technique. Well above $T_c$, the results confirm predictions obtained from the three-dimensional Heisenberg model, including the value of the crossover exponent $\phi =1.26\mathrm{}$. Analysis of deviations from quasistatic behavior near $T_c$ yields for the first time a dynamic scaling function $G\left(\omega \tau \right)$ for the critical attenuation of ultrasound. $\tau$ may be interpreted as the relaxation time of ordered clusters. We find that $\tau \approx 9\times {10}^{-13\mathrm{}}{t}^{-1.41\mathrm{}}$ s.

An irreversible change with pressure of the spin-density wave mismatch parameter $\delta$ has been observed in single-$Q$ chromium at 4.2 K. This change, which appears to be analogous to a metallurgical "hardening," can be annealed out by raising the temperature to 80 K. The pressure derivative in the "soft" mode matches that found in high-pressure de Haas-van Alphen studies while the "hard"-mode result is consistent with magnetostriction measurements; so the apparent discrepancy is resolved.

Lattice-distortion domain walls in the spin-density-wave phases of Cr are thin, have negative free energy, and provide an explanation for the irreversibility of increases of $\delta$ in $Q=\left(\frac{2\pi }{a}\right)(1\mathrm{}\pm \delta )$ with increases in pressure at $T\ll 50$ K, observed in de Haas-van Alphen experiments of Ruesink, Perz, and Templeton. Domain walls of the spin-density wave itself have positive free energies, have thickness ≳1000 Å, and cannot be used to explain these experimental results.

The first experimental comparison of ${\mathrm{Li}}^{+}$ and ${\mathrm{He}}^{+}$ scattering (primary energies between 100 and 1200 eV) from a clean Ni(110) surface shows strong variations of the ${\mathrm{Li}}^{+}$ intensity with crystal orientation, an effect which we attribute to multiple scattering. In the ${\mathrm{He}}^{+}$ case, only those ${\mathrm{He}}^{+}$ which scattered from surface atoms in single binary collisions survived as ions. The energy dependence of differential scattering cross sections is obtained from the experiments as well as the ratio of the neutralization probabilities of ${\mathrm{Li}}^{+}$ and ${\mathrm{He}}^{+}$ in the single-scattering events.

The observation of spin dephasing in an ensemble of dipolar coupled $A$ and $B$ spins is reported. In CaO crystals, the $A$-spin species are photoexcited $S=1\mathrm{}$, ${F_2}^{2+}$ centers and the group of $B$ spins consists of $S=\frac{1}{2}$, $F^{+}$ centers. Measurements were made at different temperatures and magnetic field strengths with use of coherent optical-microwave spectroscopy. For the first time, the results show that the $A$-spin dephasing is influenced by exchange narrowing in the $B$-spin ensemble.

It is shown that the dielectric response of a thin layer of $\alpha$-Sn—type semiconductor is radically different than that of the bulk material. The $q^{-1\mathrm{}}$ and ${\omega }^{-\frac{1}{2}}$ singularities of the bulk polarizability are absent in the layer. Instead, the dielectric response and optical absorption of the layer are highly anisotropic, and the static dielectric constant is linearly dependent on layer thickness. In the random-phase approximation, the thin-layer energy-band structure is unconditionally stable against exciton formation.

The distribution of magnetization in the weak itinerant ferromagnetic Ti${\mathrm{Be}}_{1.8}$${\mathrm{Cu}}_{0.2}$ has been determined by polarized-neutron diffraction. The magnetization resides on the titanium sites forming an interlocked tetrahedral network. No magnetization is present at the beryllium sites, into which copper goes substitutionally.

The palladium $3d_{\frac{3}{2},\frac{5}{2}}$ core-level satellites and valence-band satellite are studied experimentally. The nature of the former can be elucidated by a comparison with the rhodium $3d$ spectrum. A substantial chemical shift is observed for the core-level satellites in Cu-Pd alloys. The final state in the Auger process $M_5\mathrm{VV}$ is found to be quasiatomic and is identified with the valence-band satellite. As a function of copper concentration, the Auger final state and the core-level satellites undergo the same chemical shift.