Using the algebra of currents, modified Weinberg sum rules, and the tadpole model of Coleman, Glashow, and Schnitzer, we calculate the kaon electromagnetic mass difference in the soft-kaon limit to be -3.9±0.6 MeV, in excellent agreement with experiment.

Resonances recently discovered in $\pi N$ phase-shift analyses are assigned to linear Regge trajectories. The proposed classification is interpreted as evidence for (i) secondary trajectories displaced down from the leading trajectories by ${\alpha }_S\simeq {\alpha }_L-n$ ($n$ an integer) and (ii) approximate degeneracy of trajectories with opposite parity, the same signature, and equal isospin (i.e., MacDowell symmetric).

The differential cross sections for single-${\pi }^{+}$ photoproduction from hydrogen have been measured over a range of momentum transfers from -2×${10}^{-4\mathrm{}}$ to -2 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$, and photon energies from 5 to 16 GeV. The differential cross section increases by roughly a factor of 2 as the magnitude of the square of the momentum transfer decreases from 0.02 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. The cross section falls approximately as $\exp \mathrm{}(-3\mathrm{}|t\left|\right)\mathrm{}$ at large momentum transfers, with a similar momentum-transfer dependence of the cross section at all photon energies studied.

When the formal solution to the algebra of currents is saturated with vector-meson resonances, the first-order momentum dependence of $f_{+}\left(q^2\right)$ is related to $\Gamma (\omega \to {\pi }^0+\gamma )$ and is in agreement with experiments on ${K_{l3\mathrm{}}}^{+}$ and ${K_{l3\mathrm{}}}^{+}$ decays.

It is shown that if the validity of the Jacobi identity for triple equal-time commutators is assumed, then the proof for the sum rule ${g_{A_1}}^2={g_{\rho }}^2$ is not affected by the presence of $I=1\mathrm{}$ Schwinger terms, while the proof of the sum rule ${g_{A_1}}^2{m_{A_1}}^{-2\mathrm{}}+\frac{1}{2}{f_{\pi }}^2={g_{\rho }}^2{m_{\rho }}^{-2\mathrm{}}$ requires the assumption that if an $I=1\mathrm{}$ pseudoscalar Schwinger term exists, then its coupling to the pion is much weaker than that of the axial-vector current.

Anticrossing signals have been observed in resonance fluorescence in which the two repelling levels are both excited from the same level in the ground state. The two anticrossed levels both decay to the same ground-state level as well. This extension of the anticrossing technique is successfully applied in a state of the hfs of the ytterbium atom.

Tunneling from a metal into degenerate $p$-type silicon exhibits peaks in $\frac{d^{2}i}{d{V}^2}$ at biases $eV=\pm \hslash {\omega }_0$, where $\hslash {\omega }_0$ is the $k=0\mathrm{}$ optical-phonon energy of the semiconductor. It is suggested that these peaks reflect modifications in the bulk semiconductor states at energies $\hslash {\omega }_0$ above and below the Fermi energy arising from hole-optical-phonon interaction. An additional peak near the optical-phonon frequency, but well resolved from it, is identified with vibrations of the boron acceptor impurity.

We report the observation of magnetosonic waves in bismuth at microwave frequencies. The waves are characterized at low magnetic fields by a phase velocity near the Fermi velocities.