Unitarity and $\mathrm{TCP}$ invariance suffice to predict the as yet unmeasured phase ${\varphi }_{00}$ of ${\eta }_{00}$. Quite severe restrictions are placed on the parameters of $K^0\to 2\pi$ decay and exclude the particular combination favored at present.

The reaction ${\pi }^{-}p\to K_1^{}{}_{}{}^{0}K_1^{}{}_{}{}^{0}n$ has been investigated at 4 and 5 GeV/c in a spark-chamber experiment. The threshold enhancement in the $s$-wave $K_1^{}{}_{}{}^{0}K_1^{}{}_{}{}^0$ system can be fitted by either a complex scattering length or by a resonance form.

An analysis is presented of the emission of gravitational waves by a star in nonradial pulsation. This analysis, rigorous to first order in the pulsation amplitude and to all orders in $G$ and $c$, exhibits damping of the pulsation as the waves are emitted (gravitational radiation reaction).

We show that the resonance-dominance approximation for the low-energy part of finite-energy sum rules for the $C=+1\mathrm{}$, $I=0\mathrm{}$ $t$-channel $\pi N$ and $\mathrm{KN}$ elastic amplitudes reproduces correctly properties of the $P^{\prime }$ trajectory and residue functions. The Pomeranchukon is fully accounted for by the low-energy background. The Gell-Mann ghost-eliminating mechanism is favored for the $P^{\prime }$ trajectory.

Recent measurements of the $\frac{K_{\mu 3}}{K_{e3\mathrm{}}}$ relative branching ratio make possible an evaluation of the matrix element of the divergence of the vector current which is independent of $f_{+}$. The matrix element of the divergence does not depend on the mass of a possible intermediate vector boson $W$. The experimental data are best fitted by a resonance in the isospin-½ $s$-wave $K\pi$ system in the interval 750-1200 MeV.

The strong dependence of positron annihilation spectra in solid powders on particle size is shown to be indicative of positronium (Ps) diffusion in solids. Ps diffusion constants and mean annihilation lengths are estimated from measurements on powders of Si${\mathrm{O}}_2$, ${\mathrm{Al}}_2$${\mathrm{O}}_3$, and MgO. Because of Ps diffusion, positron emitters suspended in powders of very small particles constitute compact high-yield sources of free $o-\mathrm{Ps}$ and of gamma rays with continuous energy spectra.

The first observation of infrared stimulated emission associated with the optical phonons of a liquid is reported at 5μ from benzene. The variation of the $5-\mu$ output, as a function of the temperature of the benzene, is the same as the large period of the thermospectrum of the 8050-Å stimulated Raman line, which involves the same optical phonons.

Superfluid persistent currents are observed to decay with a logarithmic time dependence for flow velocities near the critical velocity. The temperature dependence of the decay rate and the critical velocity obtained from the experiment are discussed in terms of a thermal activation picture.

We have observed interactions between collimated monoenergetic beams of charged vortex rings. The cross section for ring-ring interaction is approximately geometrical, consistent with a hydrodynamic interpretation. Capture of free ions by oppositely charged rings has also been observed.

A depolarized doublet centered at the frequency of the exciting laser radiation has been observed in the light-scattering spectrum of several liquids, including nitrobenzene, aniline, quinoline, and $m-\mathrm{nitrotoluene}$. The frequency separation, line shape, and polarization characteristics suggest that this doublet arises from thermally excited shear waves in these relatively viscous liquids.

A strong decrease in the damping of Tonks-Dattner resonances with increasing strength of the exciting microwave field has been observed in low-pressure mercury and argon dc discharges. Order-of-magnitude estimates indicate that a nonlinear effect involving a balance between wave-particle and particle-particle collisions may be responsible.

The self-trapping and the modulational instability of nonlinear hydromagnetic $n$ waves of right-hand polarization in a cold plasma are discussed on the basis of a non-linear dispersive equation, which enables us to directly apply the results obtained in the nonlinear optics.

Capacitance observations of Landau levels in a two-dimensional electron gas induced in the inversion layer on a (100) surface of $p$-type silicon are reported. Evidence for surface quantization and the associated lifting of the spin and valley degeneracy are presented. An observed increase in the carrier threshold with increasing magnetic field is shown to be further evidence of surface quantization.

The interaction of two singlet excitons to produce electron carriers has been observed in anthracene for the wavelength range 315-405 nm. With an applied field of ${10}^4$ V ${\mathrm{cm}}^{-1\mathrm{}}$, the rate constant for carrier production is 0.9 × ${10}^{-12\pm 0.4}$ ${\mathrm{cm}}^3$ ${\sec }^{-1\mathrm{}}$. The rate constant for singlet-exciton second-order disappearance is 1.5 × ${10}^{-8\mathrm{}\pm 0.3}$ ${\mathrm{cm}}^3$ ${\sec }^{-1\mathrm{}}$

High-purity hollow cylinders of type-I superconductors in which the surface strains are minimal show order-of-magnitude decreases from the diamagnetic or field trapping properties described in present literature. The properties can be made to approach the predicted behavior when both surfaces are heavily strained. Both the diamagnetic and field-retaining properties are localized and can result in axial-field gradients in the void that exceed ${10}^3$ Oe/cm.

The momentum spectra of energetic deuterons in proton-nucleus collisions at 1 BeV have been calculated using Feynman-diagram techniques and are compared with the results of recent experiments.

The Weisskopf-Ewing assumption-that an ($x,yn$) reaction occurs with nearly unit probability if the first emitted particle, $y$, comes off with sufficiently low energy to make neutron emission energetically possible-is tested by coincidence studies of ($p,p^{\prime }n$) and ($p,p^{\prime }\gamma$) reactions on ${\mathrm{Sn}}^{119}$ and ${\mathrm{Ni}}^{61}$ and found to be grossly in error. In particular, ($p,p^{\prime }\gamma$) competes favorably with ($p,p^{\prime }n$) even when neutron emission is energetically possible by ∼2 MeV. In ${\mathrm{Sn}}^{119}$, the detailed shape of the energy spectrum of neutrons implies that spectra are drastically non-Maxwellian at low energies.

An analysis of the reaction ${\mathrm{Li}}^6({\pi }^{+},pp){\mathrm{He}}^4$ shows that the mechanism for transitions to the ground and excited states in ${\mathrm{He}}^4$ is dominated by a single-pole model when the momentum transfer is restricted to small values. Preferential excitation of the $T=1\mathrm{}$ levels in ${\mathrm{He}}^4$ is observed and is explained on the basis of the single-pole model.

Methods for the determination of spins and parities of nuclear states by means of measurements of the average $\gamma$-ray spectra formed by neutron capture in many resonances are described. Results for 30 low-energy states of ${\mathrm{Er}}^{168}$ illustrate the use of the average $\gamma$-ray intensity, and measurements on nuclides near $A=100\mathrm{}$ show that the $\gamma$-ray line shape can also provide valuable information.

A 171-day high-spin ($I>~10$) isomer was discovered in ${\mathrm{Ir}}^{194}$. It is predominantly formed by three successive neutron captures from ${\mathrm{Ir}}^{191}$, via successively higher spin states in ${\mathrm{Ir}}^{192}$ ($I=4\mathrm{}$) and ${\mathrm{Ir}}^{193m}$ ($I=\frac{11}{2}$). The isomer decays by $\gamma$ decay chiefly to a 2438-keV state in ${\mathrm{Pt}}^{194}$, which is depopulated by two parallel branches. The more intense branch proceeds through a "ground-state band" ($8^{+}$→$6^{+}$→$4^{+}$→$2^{+}$→$0^{+}$) whose level energies indicate that ${\mathrm{Pt}}^{194}$ is a somewhat deformed and very "soft" nucleus.