The realization of chiral SU(2) ⊗ SU(2) symmetry by nonlinear field transformations is considered from the standpoint of axiomatic field theory. We show that the communication relations of chiral symmetry are incompatible with the assumption that the pion has nonzero mass.

It is shown that (approximate) field-current identities appear in a natural way in a Yang-Mills-type theory if the local symmetry is spontaneously broken.

Finite-width corrections based on a generalized effective range formula for pion-pion scattering modify by a non-negligible amount the well-known relation between $\Gamma (\rho \to e^{+}{e}^{-})$ and $\Gamma (\rho \to \pi \pi )$ derived on the basis of vector-meson dominance. We also present a new current-algebra prediction for the shape and magnitude of $\sigma (e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-})$ and estimate the $\rho$-meson contribution to the Schwinger term.

Single ${\pi }^{-}$ and ${\pi }^{+}$ photoproduction from deuterium has been measured at gamma energies of 3.4 and 5 GeV and momentum transfers between 0.005 and 0.6 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. The $\frac{{\pi }^{-}}{{\pi }^{+}}$ ratio is found to be unity near the forward direction and drops to about 0.3 at larger angles. The data support the existence of a forward peak in ${\pi }^{-}$ photoproduction on neutrons.

We study the implications of Lorentz and gauge invariance for Reggeization of the pion trajectory in charged pion photoproduction and find that the pion need not be introduced as a kinematical singularity. As a consequence of having a dynamical Regge pion pole, we find that effects characteristic of an $s$-channel nucleon pole appear automatically.

Arguments based on experimental evidence are presented against the existence of strange leptons, as recently suggested by Weiner.

From measurements of the polarization of muons from $K_{\mu 3}^{}{}_{}{}^0$ decay, we have found the average longitudinal component to be 0.88 ± 0.25, and the average component in the plane of decay but perpendicular to the muon momentum to be 0.369 ± 0.036. From these we determined $\mathrm{Re}\xi =-{1.75}_{-0.2\mathrm{}}^{+0.5\mathrm{}}$, assuming constant form factors. The behavior of $\mathrm{Re}\xi \mathrm{}\left(0\right)\mathrm{}$ with varying form factors is discussed.

A second and more precise experiment has been performed at the Lawrence Radiation Laboratory's 184-in. cyclotron to look for any difference in the total lifetimes of ${\pi }^{+}$ and its antiparticle, ${\pi }^{-}$. Any observed difference would be direct evidence for a violation of $\mathrm{CPT}$ invariance in the weak decay of the charged pion. We find $\frac{{\tau }_{+}}{{\tau }_{-}}=1.000\mathrm{} 64\pm 0.000 69$, and thus no evidence for a $\mathrm{CPT}$ nonconservation.

A simple technique is proposed in which rf transitions between suitable energy levels of an atomic or molecular ion, a member of a stored, radiatively thermalized ion gas, may be detected by monitoring the translational temperature of the ion gas. An experimental study of the cyclotron resonance of an electron gas confined in a Penning trap demonstrates its usefulness, and possible applicability to spin resonance.

Maxwell's equations and the two-level density-matrix equations are integrated numerically under conditions which simulate the operation of a $Q$-spoiled laser. The final out-put intensity pattern takes the form of a train of sharp pulses separated by the round-trip time.

The contributions of long-range triple-dipole three-body interactions to the thermodynamic properties of dense gaseous argon are calculated using a recently developed perturbation theory together with an accurately determined pair potential function. Calculated pressures, internal energies, and critical constants are in reasonable agreement with experiment provided that the three-body contributions are included. The validity of the principle of corresponding states in the presence of three-body forces is discussed.

Dielectric losses have been measured in hexammine nickel chloride crystals, which contain a system of protons (${\mathrm{H}}^{+}$ ions) that is responsible for a motional phase transition. The losses are well approximated by Debye curves, both above and below the transition temperature. Since this transition is not accompanied by the onset of a dipolar moment, long-range forces may be neglected, as in the similar but more complex case of hydrogen-bonded ferroelectrics, and the present results may shed light on the dynamical model of this class of substances.

The electron spin-echo technique has been used to measure the spin-lattice relaxation of ${\mathrm{V}}^{4+}$ paramagnetic impurities in rutile (Ti${\mathrm{O}}_2$) at liquid-helium temperatures. The relaxation of the $z$ component of magnetization shows a time dependence, the sum of two exponentials with two time constants $T_{1a}$ and $T_{1b}$. In the liquid-helium temperature range, both time constants are independent of temperature. The relaxation times are independent of sample size and surface condition but are dependent on annealing history. The results of this study suggest that $T_{1b}$ is related to the phonon relaxation time due to crystal-defect scattering.

An unoxidized Al surface was irradiated by 50-keV electrons at grazing incidence. A peak in the spectrum of the electromagnetic radiation emitted from the target was found at an energy of 9.7 eV. It was interpreted as radiative decay of the tangential surface plasmon.

It is argued that for a system of permanent dipoles no collective excitations associated with the charge-density fluctuations exist.

Two-magnon absorption and Raman experiments create pairs of magnons in close proximity, and hence, the magnon-magnon interaction has an important effect on the spectral line shape. Green's-function methods have been used to calculate this effect and the results applied the example of cubic antiferromagnets like RbMn${\mathrm{F}}_3$. Similar techniques are used to find the effect of exciton-magnon interaction on the sidebands in RbMn${\mathrm{F}}_3$; corresponding experimental results are presented.

We report the observation of light scattering from two-magnon excitations in RbMn${\mathrm{F}}_3$. The shape and polarization of the spectrum are compared with theoretical predictions of Elliott et al. and confirm the importance of magnon-magnon interactions. Temperature dependences of the frequency and linewidth of the two-magnon spectrum are also given.

The frequency-dependent dielectric function $\epsilon \left(\omega \right)$ of an inherently zero-gap semiconductor, such as grey tin, has unusual properties at low temperatures. In undoped samples $\epsilon \left(\omega \right)\sim {\omega }^{-\frac{1}{2}}$; in doped samples interband effects considerably modify the coefficient of the additional ${\omega }^{-2\mathrm{}}$ term from its free-carrier value, the sign being reversed for $p$-type impurities. These properties should be observable in reflectance measurements.

The reactions ${\mathrm{Pb}}^{207}({\mathrm{He}}^3,d){\mathrm{Bi}}^{208}$ and ${\mathrm{Bi}}^{209}\mathrm{}(d,t)\mathrm{}{\mathrm{Bi}}^{208}$ are found to excite the single-proton states coupled to the $3p_{\frac{1}{2}}$ neutron hole in ${\mathrm{Pb}}^{208}$ and the single-neutron hole states coupled to the $h_{\frac{9}{2}}$ proton added to ${\mathrm{Pb}}^{208}$, respectively. Each particle-hole configuration forms a multiplet of states. Nine such multiplets have been identified, most of them for the first time. Tentative spin assignments based on intensities are proposed; a comparison with theoretical calculations gives remarkable agreement.

Elastic-scattering calculations for ${\mathrm{O}}^{16}$ + ${\mathrm{O}}^{16}$ by real molecular-type potentials were carried out over energies 8-30 MeV (c.m.). The cross sections are too large, although they show the erratic behavior expected in the orbiting energy range. A Blair approximation with an absorbing core of 3- to 4-F radius on these molecular-potential phase shifts gives the correct magnitude and energy dependence of the excitation function from 17 to 26 MeV.