We have studied properties of strange-particle final states arising from reactions of 1.1- to $2.4-\frac{\mathrm{GeV}}{c} {\pi }^{+}$ mesons on deuterium. Total cross sections on deuterium are presented and three reactions are analyzed in terms of the impulse model. $Y^{*}\mathrm{}\left(1385\right)\mathrm{}$ production dominates the $n\Lambda K^{+}{\pi }^{+}$ final state, and the reaction is described adequately near threshold by a magnetic dipole $K^{*}$ exchange model. The $n{\Sigma }^{+}{K}^0{\pi }^{+}$ final state is found to be primarily $n{\Sigma }^{+}{K}^{*+}$. Highly aligned $\phi$'s are produced in the reaction ${\pi }^{+}d\to \mathrm{pp}{K}^{+}{K}^{-}$, along with $\Lambda \mathrm{}\left(1520\right)\mathrm{}$.

We have analyzed the Dalitz-plot distribution of the two dominant charged decays of the $\eta$ meson. From 7250 examples of $\eta \to {\pi }^{+}{\pi }^{-}\gamma$, we find that the $\gamma$-ray energy spectrum disagrees with the simplest gauge-invariant matrix element corresponding to the dipion in the $J=1\mathrm{}$ state. However, it agrees well with a simple $\rho$-dominant model. The ${\pi }^0$ energy spectrum of 30 000 examples of $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$ was fitted to a power-series expansion of the matrix element in the usual Dalitz coordinates. We find that a matrix element linear in the ${\pi }^0$ kinetic energy does not fit our data. We measure the branching ratio $\frac{\eta \to {\pi }^{+}{\pi }^{-}\gamma }{\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0}$ to be 0.201±0.006.

Based on 150 000 photographs taken with the 30-in. bubble chamber at the ZGS, we present a study of the $\overline{p}d\to p_s\overline{p}p{\pi }^{-}$ reaction. Important production of ${\overline{\Delta }}^{--}\mathrm{}\left(1236\right)\mathrm{}$ is observed. The distribution of the momentum transfer between the incident $\overline{p}$ and the final ${\overline{\Delta }}^{--}\mathrm{}\left(1236\right)\mathrm{}$ is compared with data at other energies and also with the crossed $\mathrm{pp}\to {\Delta }^{++}n$ reaction. That the peaking of the momentum transfer tends to be greater for the $\mathrm{pp}\to {\Delta }^{++}n$ than for the $\overline{p}n\to {\overline{\Delta }}^{--}p$ reaction at 5.5 $\frac{\mathrm{GeV}}{c}$ can be explained by using a simple Regge-pole model. For events produced without resonance in the final state, the longitudinal phase-space analysis is applied to the data. For these events, an attempt was also made to use a double Regge-pole model to describe the production. The present version of this model reproduces the experimental data fairly well. Using the Fermi motion of the neutron target, we try to extract information about the variation of the $\overline{p}n\to \overline{p}p{\pi }^{-}$ cross section with c.m. energy. In connection with this problem, a discussion on the validity domain of the impulse approximation is given.

One of the classic "null experiments" tests the exactness of the electrostatic inverse-square law. The outer shell of a spherical capacitor is raised to a potential $V$ with respect to a distant ground, and the potential difference $\Delta V$ induced between the inner and outer shells is measured. If this induced potential difference is not zero, Coulomb's law is violated. For example, if we assume that the force between charges varies as $r^{-2+q}$, then $\frac{\Delta }{V}$ is approximately a tenth of $q$. In our experiment five concentric spheres are used. A potential difference of 40 kV at 2500 Hz is impressed between the outer two spheres. A lock-in detector with a sensitivity of about 0.2 nV measures the potential difference between the inner two spheres. We find $\mathrm{}\left|q\right|\mathrm{}\le 1.3\times {10}^{-13\mathrm{}}$. We also find comparable limits on the detected signal when the operating frequency is 250 Hz, and when the detector is synchronized with the charging current rather than with the charge itself.

The reactions $\overline{p}n\to \overline{p}n{\pi }^{+}{\pi }^{-}$, $\overline{p}n\to \overline{p}p{\pi }^{-}{\pi }^0$, and $\overline{p}n\to \overline{n}p{\pi }^{-}{\pi }^{-}$ at $2.8-\frac{\mathrm{GeV}}{c}$ incident $\overline{p}$ laboratory momentum are analyzed with data from the Brookhaven National Laboratory 20-in. bubble chamber. $N^{*}\mathrm{}\left(1238\right)\mathrm{}$ isobar production in these channels is studied. It is found that the absorptive single-pion-exchange model cannot adequately explain all the features of simultaneous isobar production in these reactions. When the reactions $\overline{p}n\to ({\overline{N}}^{*--}{N}^{*+} or {\overline{N}}^{*0\mathrm{}}{N}^{*-})\to \overline{p}{\pi }^{-}n{\pi }^{+}$ are compared with their counterpart $\mathrm{pp}\to N^{*++}{N}^{*0\mathrm{}}\to \mathrm{pp}{\pi }^{+}{\pi }^{-}$, the former are found to be less peripheral than the latter, in sharp disagreement with a prediction of the model. A generalized single-pion-exchange model is discussed which gives better agreement with the nucleon-pion two-body mass and angular distributions. Some evidence for enhancements in the nucleon and antinucleon dipion systems at 1400 MeV is discussed.

The Princeton-Pennsylvania accelerator 15-in. hydrogen bubble chamber was used to investigate ${\pi }^{+}p$ associated production at 1.7 $\frac{\mathrm{GeV}}{c}$. Approximately 4000 events were found; about half of these were in the ${\Sigma }^{+}{K}^{+}$ channel. The $\Lambda K^{+}{\pi }^{+}$ channel dominates the remaining half of the data. We find evidence for the existence of a $T=1\mathrm{}$ hyperon resonance at 1475±15 MeV with a width of 30±15 MeV in the $\Lambda K^{+}{\pi }^{+}$, ${\Sigma }^{+}{K}^{+}{\pi }^0$, ${\Sigma }^0{K}^{+}{\pi }^{+}$, and $P{K}^{+}{\overline{K}}^0$ channels. The cross sections of the strange-particle channels and the branching ratios of various resonances are also presented.

Polarization of $\Lambda$ hyperons and differential cross sections for the reaction $\gamma +p\to K^{+}+\Lambda$ were measured at the $K^{+}$-meson center-of-mass angles around 45°, 70°, and 90° for the incident photon energies of 1054, 1100, and 1160 MeV. The $K^{+}$ mesons were detected with a magnetic spectrometer and a velocity-selection system based on the energy loss and the time of flight. The polarization of $\Lambda$ was determined by measuring the up-down asymmetry of protons in the decay $\Lambda \to p{\pi }^{-}$ with respect to the production plane. The results show a dominant $sin\theta _K^{}{}_{}{}^{*}$ dependence of the polarization at the region of the third resonance and are consistent with a contribution of the $P_{11}$ resonance with a mass of about 1700 MeV.

Results are presented on the properties of ${\pi }_N\mathrm{}\left(980\right)\mathrm{}$, produced peripherally in the reaction $K^{-}+p\to Y_1^{}{}_{}{}^{*+}\mathrm{}\left(1385\right)+\pi _N^{}{}_{}{}^{-}\mathrm{}\left(980\right)\mathrm{}$ with a cross section of 9±3 μb at 5.5 $\frac{\mathrm{GeV}}{c}$. A search was made for ${\pi }_N\mathrm{}\left(980\right)\mathrm{}$ production via the decay of a higher-mass resonance. The cross section for the reaction $K^{-}+p\to \Lambda +D^0\mathrm{}\left(1285\right)\mathrm{}$ at 5.5 $\frac{\mathrm{GeV}}{c}$, with the subsequent decay $D^0\to {\pi }_N\mathrm{}\left(980\right)+\pi$, was <6 μb at the 70% confidence level. The mass and width of the ${\pi }_N\mathrm{}\left(980\right)\mathrm{}$ are 980±10 and 80±30 MeV, respectively. The dominant decay mode is $\pi \eta$, with the decay angular distribution having about a 10% probability of being isotropic. At the 70% confidence level, the branching ratio into $\pi \rho$ relative to $\pi \eta$ is <0.25, and the amount of any $K^{-}{K}^0$ enhancement near 1 GeV, normalized to the ${\pi }^{-}\eta$ signal from $\pi _N^{}{}_{}{}^{-}\mathrm{}\left(980\right)\mathrm{}$ decay, is <0.2.

The cross section for the reaction $\gamma +\mathrm{C}\to e^{+}+e^{-}+\mathrm{C}$ has been measured for a series of kinematic points giving nuclear momentum transfers in the region 0.2-0.7 ${\mathrm{F}}^{-2\mathrm{}}$, with incident photon energies in the region for photoproduction of the first two pion-nucleon resonances. Measurements were made, using asymmetric detection geometry, of electron and positron cross sections for each point. The charge-independent yields are shown to be in agreement with predictions of quantum electrodynamics for coherent and quasi-elastic production on carbon. The charge-asymmetric results are shown to be consistent with recent estimates of the interference between Bethe-Heitler and Compton pair production amplitudes with excitation of an intermediate $\pi -N$ state in the Compton diagram.

Some general remarks regarding static metrics with axial symmetry are made. A particular solution of this class for the interior of a body which joins smoothly with the exterior general Weyl fields at the boundary of the body is discussed. This solution, though it shows all the features of a solution recently discussed by Marek, is better in the sense that the matter admitted by it is physically more reasonable.

The $\mathrm{npd}$ vertex, Ward and Jacobi identities are used to evaluate the equal-time commutator (ETC) of the deuteron axial vector with the nucleon field. Schwinger terms are shown to be related to the deuteron wave function. They are important for nuclear short-range correlations. Ward identities yield the pole-term amplitudes for $\mathrm{pp}\to d{\pi }^{+}$ and $\mathrm{pn}\to d\gamma$ at threshold. Pion-induced nucleon-nucleon scattering is traced to the deuteron ETC with the weak axial-vector current. The Bjorken limit with respect to the deuteron yields the nonrelativistic limit of the reaction amplitudes.

We present a simple derivation of the angular condition on current algebra at infinite momentum, wide enough to cover the possible presence of spacelike states. The use of the Breit frame, which is not in general possible if spacelike states are involved, is completely avoided.

The effect of weak neutral currents in astrophysics is studied. A major effect is to reduce the effective $e\nu$ coupling by one-half. A new (minor) source of neutrino emission is shown to exist to first order in the weak and electromagnetic coupling.

The universality of the slopes of meson trajectories is established in the context of the Veneziano model from the postulate of asymptotic $\mathrm{SU}\left(3\right)\mathrm{}\times \mathrm{SU}\left(3\right)\mathrm{}$ symmetry and without reference to the Adler consistency conditions.

Polkinghorne's exact perturbation-theory equation for the leading Regge trajectory resulting from an infinite sum of ladder diagrams is shown to be mathematically equivalent to the partial-wave Bethe-Salpeter equation. Thus, the perturbation-theory equation can be used not only for the leading Regge trajectory, but for all secondary trajectories as well.

The various implications of a transformation recently suggested by Kuo in the model of Gell-Mann, Oakes, and Renner have been investigated.

In this paper we explore the general features of non-vector-dominance Veneziano models for $A^{\mu }\pi \to \pi \pi$. We assume that the axial-vector current is conserved (zero-mass pions) and write our invariant amplitudes as products of beta functions and arbitrary functions of the axial-vector-current momentum squared. By using a soft-pion theorem, we are able to make statements about the pion form factor. In a particular model of the above type (the spurion model applied to the five-point function) we find that $F\left(q^2\right)=\frac{{\pi }^{-1\mathrm{}}\Gamma \left(\frac{1}{2}\right)\Gamma (-q^2+\frac{1}{2})\Gamma (-{\gamma }_2+\frac{1}{2})}{\Gamma (-q^2-{\gamma }_2+\frac{1}{2})}.$

Recently Regge effects have been studied in weak amplitudes by describing the final-state strong interaction with a Regge pole at $J=\phi \mathrm{}\left(t\right)\mathrm{}$. In particular, it has been shown that the double-helicity-flip amplitude $A_1\mathrm{}(s,t)\mathrm{}$ for the process $\gamma \pi \to \gamma \pi$ has a moving pole at $J=\phi \mathrm{}\left(t\right)-2\mathrm{}$ and a fixed pole at $J=-1\mathrm{}$, and that the electromagnetic form factor of the pion, $F_{\pi }\mathrm{}\left(s\right)\mathrm{}$, can be written as $F_{\pi }\mathrm{}\left(s\right)=1+G_P\mathrm{}\left(s\right)+G_{\rho }\mathrm{}\left(s\right)\mathrm{}$, where $G_{\rho }\mathrm{}\left(s\right)\mathrm{}\to s^{\phi \mathrm{}\left(0\right)-1\mathrm{}}[1+O(\frac{1}{\ln s}\left)\right]$. In the present paper, we demonstrate how these results can be obtained by a simple and direct method that draws out an immediate physical understanding of the results obtained. Our method involves the study of the asymptotic behavior of the relevant field-theoretic diagrams with the use of Sudakov variables.