It is shown that when the Dirac theory is formulated in the formalism of the dynamical group O(4, 2), there is no need to invoke the hole theory or the notion of backward motion in time to describe antiparticles. A single irreducible representation of O(4, 2) is used and the discrete operators $P$, $C$ become inner automorphisms of the group. The most general linear minimal parity-violating equation generalizing the Dirac equation is shown to lead to two possible distinct mass values.

A prominent peak observed in the soft x-ray continuum emission of a deuterium-neon plasma is associated with radiation from the two-photon decay of the $2{}_{}{}^1{}_{}{}^{}S$ "metastable" state of heliumlike Ne IX.

The polarizability of closed atomic shells near field inhomogeneities is discussed in connection with several problems of physical interest. We find that magnetically "neutral" $S=0\mathrm{}$ atoms or closed shells are attracted and polarized by magnetic field gradients. The effect is demonstrated through sample calculations for noninteracting as well as for interacting electrons.

We report the first observation of the NMR of a localized magnetic moment in a metal at temperatures far below its Kondo temperature. The system studied is dilute solid solutions of vanadium (0.1-10 at.%) in gold. We detect the partially spin-compensated $d$-spin magnetization of the impurities for the lowest concentration, and evidence for interaction between the impurities at higher concentrations.

We have measured the ratio of yields for a single porton transferred into versus out of a projectile in reactions involving four different heavy projectiles on each of five heavy targets. There is a strong preference to transfer the proton out of the projectile, which can be understood in terms of the potential energy of the two nuclei near contact.

Observations of high-energy photons geomagnetically trapped in the inner Van Allen belt have been carried out since September 1962. Between November 1962 and June 1966, the omnidirectional proton flux at 63 MeV remained constant to within ±7.6%. However, since August 1966 we have obtained substantial evidence that the proton flux is decreasing in a manner which is attributable to solar-cycle variations in the density of the upper atmosphere.

We derive sum rules for the spectral functions associated with the propagator function for the generalized stress-energy tensor. Saturation of these sum rules with $2^{+}$ and other mesons is then considered. This leads to some new and interesting mass formulas, which we discuss.

We have measured the mean life of ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^3{}_{}{}^{}$ to be (${2.32}_{-0.34\mathrm{}}^{+0.45\mathrm{}}$)×${10}^{-10\mathrm{}}$ sec. This does not agree with previous measurements but is completely consistent with theoretical expectations.

The electric dipole moment of HD in its ground vibrational and electronic state has been obtained from the intensity of the pure rotational spectrum. Its value is (5.85±0.17) × ${10}^{-4\mathrm{}}$ D.

Diffraction theory is applied to elastic and inelastic scattering of charged particles by hydrogen atoms. At small momentum transfers the calculated intensities for elastically scattered electrons are significantly greater than those calculated by the first Born approximation.