The observed diffuse x- and $\gamma$-ray spectrum is analyzed, and consequences are deduced for Compton-scattering models in intergalactic space. The putative far-infrared radiation is examined for its effects on (1) interpretation of the diffuse x- and $\gamma$-ray observations, (2) Compton-scattering models in galactic and intergalactic space, and (3) the cosmic-ray electron spatial distribution in our galaxy.

The problem of detecting faster-than-light particles is reconsidered in relation to Tolman's paradox. It is shown that some of the experiments already under way or contemplated must either yield negative results or give rise to causal contradictions.

Results are presented of a bubble-chamber study of the interaction of negative kaons with helium yielding $\Lambda {\pi }^{-}$ or ${\Sigma }^0{\pi }^{-}$ in the final state. Both low-momentum kaons and kaons at rest were used. In the at-rest sample, the two-step process $K^{-}N\to \Sigma \pi$ followed by $\Sigma N\to \Lambda N$ accounts for (18±2)% of the $\Lambda {\pi }^{-}{\mathrm{He}}^3$ final state. Removing these $\Sigma -\Lambda$ conversion events, on the basis of the pion kinetic energy, gives spectra that are compared with an impulse model. A good fit to the data is obtained by using a Hulthén form factor, a mixture of atomic-orbital-capture states with (71±9)% $s$ state and (29±9)% $p$ state. For this fit, the $S$-wave $\overline{K}N$ amplitude determined by Kim is used, and the $P$-wave amplitude is assumed to be dominated by the $Y^{*}\mathrm{}\left(1385\right)\mathrm{}$ with the coupling to $\overline{K}N$ given by $\mathrm{SU}\left(3\right)\mathrm{}$ symmetry. The same final state initiated by kaons in flight shows a good agreement with the predictions of the impulse model. No evidence is seen for a recently reported enhancement in the $\Lambda {\pi }^{-}$ system at 1440 MeV. The $\Lambda {\pi }^{-}\mathrm{pd}$ final state is found to be dominated by the $\Sigma -\Lambda$ conversion process. Stopping-$K^{-}$-reaction branching ratios and cross sections are calculated and compared with impulse-model predictions. No evidence is found for a $\Lambda n$ bound state, and an upper limit for its production is 5×${10}^{-4\mathrm{}}$ per stopping $K^{-}$.

We have obtained 459 events of the type ${\pi }^{-}p\to {\pi }^{-}{\pi }^{-}{\pi }^{-}{\pi }^{+}{\pi }^{+}p$ at 3.9 $\frac{\mathrm{GeV}}{c}$. The cross section is found to be 0.115±0.011 mb. Strong ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$ production is observed, along with the production of ${\rho }^0$ in association with the ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$. A statistically significant ${A_1}^{-}$ signal is present. An anomalous enhancement is observed at 1.4-GeV ${\pi }^{+}{\pi }^{+}p$ mass which is mainly caused by the strong ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$ production. No meaningful structure is seen in any of the four- or five-body invariant-mass spectra. The data have been fitted with a model of incoherent resonance production.

A spark-chamber experiment is described which measured the distribution in the Dalitz plot of 3140 ${K_{\mu 3}}^0$ decays, and measured the branching ratio $\frac{\Gamma (K_L\to \pi \mu \nu )}{\Gamma (K_L\to \pi e\nu )}$. From a study of the Dalitz plot, a ratio of form factors $\xi =-3.9\mathrm{}\pm 0.4$ is found with little or no energy dependence. The branching-ratio measurement gives a value $\xi =-0.5\mathrm{}\pm 0.5$ which is incompatible with the Dalitz-plot result. The results are discussed from the point of view of possible experimental bias. The results are compared with other experiments.

We have measured the asymmetry parameter ${\alpha }_{-}$ for the nonleptonic decay ${\Sigma }^{-}\to n+{\pi }^{-}$ as well as the asymmetry parameter ${\alpha }_{\mathrm{lept}}$ for the leptonic decays ${\Sigma }^{-}\to n+e^{-}+{\overline{\nu }}_e$ and ${\Sigma }^{-}\to n+{\mu }^{-}+{\overline{\nu }}_{\mu }$, using polarized ${\Sigma }^{-}$ produced in the reaction $K^{-}+p\to {\Sigma }^{-}+{\pi }^{+}$ in the vicinity of the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ resonance. Measurements were carried out on the Yale Precision Encoding and Pattern Recognition (PEPR) system, and leptonic decays were subjected to gap-length analysis. Using the ${\Sigma }^{-}$ polarization function of Thompson, we find ${\alpha }_{-}=-0.067\mathrm{}\pm 0.011$ based on 60 000 two-body decays; ${\alpha }_{\mathrm{lept}}=+0.23\mathrm{}\pm 0.44$ based on 44 electron decays; ${\alpha }_{\mathrm{lept}}=+0.36\mathrm{}\pm 0.39$ based on 44 electron decays and 19 muon decays. Our value of ${\alpha }_{\mathrm{lept}}$ yields a ratio of axial-vector to vector matrix elements given by $\frac{g_A}{g_V}=-0.33_{-0.85\mathrm{}}^{}{}_{}{}^{+0.39\mathrm{}}$, using a sign convention in which this ratio is negative for the neutron. While our data favor a negative sign for this ratio (in disagreement with the Cabibbo theory), a positive sign cannot be excluded.

We have measured the photoproduction of electron-positron pairs from carbon using an improved version of the Harvard pair spectrometer. The bending magnet and two half-quadrupole magnets were retained. For each half-quadrupole, a tungsten collimator was added at the entrance, a portion of the lead obstacle was removed, and a defining counter was added at the midpoint. Faster counting electronics and an on-line computer were employed. Pairs were detected in an invariant-mass range of 97-445 MeV. The results are in agreement with the predictions of quantum electrodynamics and may be parametrized as $R=(1.09\mathrm{}\pm 0.07)\times [1+({{31.6}_{-41.2\mathrm{}}}^{+31.2\mathrm{}})\times {10}^{-8\mathrm{}}{Q_M}^2]$. Here $R$ is the ratio of experiment to theory, and $Q_{M^2}$ is the electron-pair mass squared ($\frac{{\mathrm{GeV}}^2}{c^4}$). The errors include both statistical and systematic effects. In the course of this work, we have also derived an accurate approximation for the electron-pair cross section.

A series of experiments has been carried out to study the velocity dependence of the helicity $\mathcal{H}$ of $\beta$ particles from the allowed Gamow-Teller decay in ${\mathrm{Co}}^{60}$. The energies examined were varied from 205 keV ($\frac{v}{c}=0.7\mathrm{}$) to 50 keV ($\frac{v}{c}=0.41\mathrm{}$), a region where the velocity is changing rapidly with energy, and where several other measurements have reported deviations from $\mathcal{H}=-\frac{v}{c}$. We have not observed any discrepancy with a $-\frac{v}{c}$ dependence for the helicity within a measurement accuracy of a few percent at the highest velocities and 9% at the lowest velocity. The weighted mean of the helicity measurements is $-\frac{\mathcal{H}}{\left(\frac{v}{c}\right)}=1.014\mathrm{}\pm 0.018$. Assuming, in turn, either the two-component neutrino theory with predominantly axialvector interaction or the absence of any tensor interaction admixture, this result limits the ratio $\frac{C_T}{C_A}$ to <0.0029, and the ratio $\frac{C_A^{\prime }}{C_A}$ to values between 0.90 and 1.11. The helicity was analyzed by Mott scattering after transformation of the polarization from longitudinal to transverse. A screened Mott scattering function $S\left(\theta \right)$ was used in the analysis. The behavior of depolarization effects and the other systematic errors associated with the technique as a function of $\beta$-particle energy was investigated extensively, and the influence of these effects on the results is reported.

We report on a study of the interactions of $4.48-\frac{\mathrm{GeV}}{c} K^{-}$ mesons on deuterium. The 372 000-picture exposure was taken in the Argonne National Laboratory 30-in. deuterium-filled bubble chamber. The ${\overline{K}}^0$ final states from the one- and two-prong-plus-vee topologies are discussed. The final states investigated include (1) ${\overline{K}}^0{\pi }^{-}\mathrm{pn}$, $\mathrm{}\left(2\right)\mathrm{} {\overline{K}}^0{\pi }^{-}d$, $\mathrm{}\left(3\right)\mathrm{} {\overline{K}}^0{\pi }^{-}{\pi }^{0}d$, $\mathrm{}\left(4\right)\mathrm{} {\overline{K}}^0{\pi }^{-}p$ (missing mass). Production of the $K^{*-}\mathrm{}\left(890\right)\mathrm{}$ resonance is analyzed from both $K^{-}-\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{t}\mathrm{o}\mathrm{n}$ and $K^{-}-\mathrm{n}\mathrm{e}\mathrm{u}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{n}$ interactions and is compared with absorption and Regge-pole models. The production of ${\Delta }^{-}\mathrm{}\left(1236\right)\mathrm{}$ in reaction (1) is compared with the predictions of Thews and with those of Maor and Krammer. Strong $K^{*-}\mathrm{}\left(890\right)\mathrm{}$ production occurs in reaction (2), and evidence for dominant-vector-meson exchange is given. The $d^{*}$ enhancement is quite strong in (3), and $K^{*}{d}^{*}$ production is discussed.

A Veneziano model is proposed for the reaction ${\pi }^{-}p\to \eta n$. This reaction is interesting since only the $A_2$ trajectory can contribute in the $t$ channel, and only $T=\frac{1}{2}$ trajectories appear in the $s$ and $u$ channels. We limit the terms in our model to those which have leading asymptotic behavior in two channels. We emphasize the intimate connection between resonance parameters and both forward and backward cross sections.

The Bell-Steinberger unitarity condition is used to discuss the relation between the phase ${\phi }_W$ of the "unitarity sum" appearing in that relation and the Lee-Wolfenstein phase ${\phi }_{\epsilon }$, for which an explicit formula is given in terms of $\left|\epsilon \right|$, ${\gamma }_1$, ${\gamma }_2$, and $m_2-m_1$.

We show how electron-positron annihilation into $\eta$ and ${\pi }^0$ may be used to obtain information on $C$ invariance in the electromagnetic interactions of hadrons. This is illustrated by studying the angular distributions in the c.m. system, the analysis of which should give a model-independent check on the validity of $C$ invariance.

On the basis of analyticity, crossing, and positivity of the imaginary parts of the partial-wave amplitudes, we derive inequalities on integrals involving the low partial waves of elastic ${\pi }^0{\pi }^0$ scattering in the physical region. The integrals are sensitive only to the low-energy region, and can therefore be tested once a phase-shift analysis is given. The relations can be used to discriminate between various proposed ${\pi }^0{\pi }^0$ phase shifts.

A simple ansatz for the isovector Dirac form factor is examined. A fit to an approximate dipole form is achieved, and deviations from this form are also accounted for. A ${\rho }^{\prime }$ is no longer necessary; the next vector meson used in the saturation has a mass of approximately 1.7 GeV. The fit also gives a $\rho \mathrm{NN}$ coupling constant which has the right value, as well as providing a good value for the necleon charge radius.

The magnetic moments of the charged octet baryons are calculated in the lowest-order nonvanishing Padé approximation assuming pseudoscalar Yukawa coupling between the octet baryons and pseudoscalar octet mesons. The experimental value is used for the pion-nucleon coupling constant. For the other coupling constants, the $S{U}_3$ values are assumed. It is found that $\alpha =0.725\mathrm{}$ ($\alpha$ being the $\frac{F}{D}$ mixing parameter, ${\alpha }_{\mathrm{expt}}=0.75\mathrm{}\pm 0.03$) reproduces the experimental value of the proton magnetic moment. Using this value of $\alpha$, one obtains ${\mu }_{{\Sigma }^{+}}=1.48\mathrm{}$, ${\mu }_{{\Sigma }^{-}}=-0.31\mathrm{}$, and ${\mu }_{{\Xi }^{-}}=-0.22\mathrm{}$ for the total magnetic moments in proton magnetons.

The amplitude for the process $\gamma \pi \to \pi \pi$ given in terms of a five-point generalized Veneziano function is shown to remove an inconsistency in the application of the Veneziano method to the process $\pi +N\to \pi +N+\gamma$ in which the first process is known to dominate. A determination of the relevant residue function consistent with other information leads to a value of the neutral pion lifetime in good agreement with experiment, provided use is made of the idea of effective width of the $\rho$ meson.

The integral equation approach to the multi-Regge peripheral model is applied to give the missing-mass spectrum with Regge behavior in $s$ and $M^2$. A simple factorizable model for the double Regge coupling then gives the magnitude and $t$ dependence of the cross section. This model is found to be in reasonable agreement with the backward ${\pi }^{-}+p\to p+X^{-}$ data.

In this paper we derive bounds on the nucleon form factor, the anomalous magnetic moment of nucleons, and the pion form factor. By using sidewise dispersion relations and the Schwarz inequality, we are able to bound the elastic nucleon form factors $F_1\left(q^2\right)$ and $F_2\left(q^2\right)$ by integrals over the structure functions for inelastic electron-nucleon scattering, $W_{1,2}(q^2,\nu )$. At $q^2=0\mathrm{}$, we then use unitarity to bound the anomalous magnetic moment by an integral over the nucleon propagator spectral function. Finally, by dispersing in $q^2$, the photon virtual mass, we are able to bound the pion form factor $F_{\pi }\left(q^2\right)$ by an integral over the total electron-positron annihilation cross section.

A model for residues of odd- and even-signature trajectories is presented which successfully accounts for the presence of dips in the differential cross sections of two-body reactions near the forward directions.

Low-$t$ theorems for charged-pion photoproduction are proven on the basis of gauge-invariance restrictions. They can be simply formulated by means of the minimal gauge-invariant extension of pion exchange (MPE). It is shown that whereas MPE leads in $\gamma N\to {\pi }^{\pm }N$ only to weak restrictions for $\frac{d\sigma }{\mathrm{dt}}$ near the forward direction ($\mathrm{}\left|t\right|\mathrm{}\lesssim {\mu }^2$), it does actually account for all the structure observed in $\gamma p\to {\pi }^{-}{\Delta }^{++}$ in this $t$ domain. Results for these reactions as well as the other charge modes of $\gamma N\to {\pi }^{\pm }\Delta$ are discussed and compared with experiment.