The generalized Veneziano model is used in a phenomenological description of the process $K^{-}p\to K^{*-}{\pi }^{+}n$. Reasonable agreement with the main features of the experimental data for 6.0 and 10.0 GeV/c is obtained.

We have formulated the continuous dispersion sum rules (CDSR) for pion photoproduction. Attempts are made to find the intercepts of the Regge trajectories at $t=0\mathrm{}$, using the result of a partial-wave analysis by Walker, and by Berends, Donnachie, and Weaver. We have, in all, analyzed the twelve regularized $t$-channel helicity amplitudes. While reasonable results are obtained for the trajectories associated with the antisymmetric isovector [(-)] amplitudes, results for the symmetric isovector [(+)] amplitudes (in particular, the $\omega$ trajectory) are inconsistent with what we expect from hadron physics. This phenomenological analysis for $\gamma N\to \pi N$ is plagued with the additional degrees of freedom allowed by the electromagnetic nature of the reaction. It is also possible that the cutoff energy used in the CDSR is not high enough. Further investigation in the analysis of the data is necessary. In connection with the study of the helicity amplitudes for pion photoproduction, we also obtain, by eliminating the invariant amplitudes, the crossing relation between the $s$- and $t$-channel amplitudes, without recourse to the crossing matrix.

A crossing-symmetric Regge-behaved amplitude for $\pi N$ scattering is constructed with a minimum number of Veneziano terms from $\rho$, ${\rho }^{\prime }$, $P^{\prime }$, and $P^{\prime \prime }$ trajectories in the $t$ channel and $N_{\alpha }$, $N_{\gamma }$, and ${\Delta }_{\delta }$ trajectories in the $s$ and $u$ channels. The parameters are determined from low-energy $\pi N$ resonances, isospin selection rules, and $\rho$ universality. The model fits the high-energy charge-exchange differential cross sections in the forward direction, and also predicts polarization in reasonable agreement with experimental values. The resulting backward elastic differential cross sections are discussed.

A covariant formulation of nucleon-nucleon bremsstrahlung is presented which is unitary and gauge invariant, and has a relatively simple form in the soft-photon limit. Applying the soft-photon approximation to experiment, a large discrepancy is found with the noncoplanar data taken in Harvard geometry, while the fit for the coplanar case is good. The inclusion of non-soft-photon dynamics using $S$-matrix methods is discussed.

The proton polarization in elastic electron-proton scattering is calculated. In order to calculate the imaginary part of the scattering amplitude, unitarity is used taking only the electron-proton state as the intermediate state. The maximum magnitude of the polarization for energies near about 1 GeV/c is ∼0.2%. The energy value at which the polarization vanishes independently of scattering angles is found.

A double-Regge-exchange model is compared to the reaction ${\pi }^{+}p\to {\pi }^{+}{\rho }^{0}p$ at 13.1 GeV/c. The reaction is well described if two diagrams ($\pi$-Pomeranchukon exchange and $\rho$-Pomeranchukon exchange) are added incoherently.

We have measured the polarization of neutrons produced in the collision of an unpolarized 3-GeV proton beam with a Pt target. The neutrons studied had kinetic energies of 300, 430, and 570 MeV and were emitted at an angle of 34° to the left of the incident proton beam. The polarization of these neutrons was deduced from a measurement of the left-right asymmetry in a subsequent charge-exchange scattering off a hydrogen target. At the above neutron energies, we find neutron polarizations of +0.056±0.023, +0.035±0.027, and +0.043±0.018, respectively. The plus sign indicates an upward polarization.

This report is based on the study of 2300 events representing the ${\pi }^{-}{\pi }^{+}{\pi }^{-}p$ final state produced by the interactions of 5.97-GeV/c ${\pi }^{-}$ mesons with protons in the Argonne National Laboratory 30-in. hydrogen bubble chamber. This final state has a cross section of 1.39±0.15 mb and is dominated by ${\rho }^0$ production (0.60±0.08 mb) and ${\Delta }^{++}\mathrm{}\left(1236\right)\mathrm{}$ production (0.39±0.06 mb). There is evidence for the production of $A_1$ and $A_{1.5}$ mesons in the $3\pi$ mass spectrum in addition to the $A_2$. Some characteristics of the $\pi \rho p$ and $\pi \pi \Delta$ final states can be explained with a double-Regge-exchange model.

In a study of the production mechanism of quasi-two-body final states at the five incident ${\pi }^{+}$ momenta 2.95, 3.2, 3.5, 3.75, and 4.08 GeV/c, approximately 40 000 events with four outgoing charged particles were investigated. The cross sections for the processes ${\pi }^{+}p\to N^{*++}\rho$, ${\pi }^{+}p\to N^{*++}\omega$, ${\pi }^{+}p\to N^{*++}\eta$, and ${\pi }^{+}p\to N^{*++}f$ have been measured as a function of the pion energy. The differential cross sections and the decay density-matrix elements are discussed in terms of one-meson-exchange models [with absorption (OPEA) and with form factor (OPEW)] and Regge models. For the $N^{*++}\rho$ and the $N^{*++}\omega$ reactions, the joint-decay matrix elements are calculated. The formation of $N^{*}\mathrm{}\left(2850\right)\mathrm{}$ in the direct channel is also investigated.

This paper presents differential cross sections for backward ${\pi }^{-}p$ elastic scattering in the angular region $-0.55\mathrm{}\ge {cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\ge -0.98\mathrm{}$ for five incident momenta: 2.38, 2.50, 2.65, 2.80, and 3.00 GeV/c. The structure of the angular distribution undergoes a marked change over this momentum interval. A pronounced dip near 180°, which is seen for momenta ≲2.50 GeV/c, becomes a sharp peak at 2.80 and 3.00 GeV/c. A minimum in the cross section at ${cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\simeq -0.7\mathrm{}$ is indicated at all momenta. In addition, a dip in the differential cross section appears at ${cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\simeq -0.92\mathrm{}$ at 3.00 GeV/c. A good fit to the data from 2.1 to 3.0 GeV/c is obtained with a direct-channel resonance model.

The restricted energy loss of electrons, positrons, protons, and pions passing through nuclear emulsions has been measured by observation of the variation in blob and grain density as a function of $\gamma =\frac{1}{{(1-{\beta }^2)}^{\frac{1}{2}}}$. All measurements were made in small areas (7 ${\mathrm{cm}}^2$) of two Ilford $K-5\mathrm{}$ emulsion pellicles. A careful examination of the variation of blob density with track depth was made in both pellicles. The results of our measurements on the relativistic rise ($5<\mathrm{}\gamma <36\mathrm{}$) as well as on the Fermi plateau ($\gamma >100\mathrm{}$) are in agreement with the predictions of the Sternheimer formula using a mean ionization potential $I$ of 434 eV and a cutoff energy $W_0$ of 6-10 keV. An upper limit of 1% is placed on radiative corrections of the type predicted by Tsytovitch. Correction for the finite number of developable grains traversed by the primary produced a best fit with $W_0=6\mathrm{}$ keV, in excellent agreement with the maximum energy of a $\delta$ ray that comes to rest within the working volume of blob counting.

The validity of the $\Delta S=\Delta Q$ rule has been tested by studying the time distributions of leptonic decays of neutral $K$ mesons produced in the reaction $K^{+}d\to K^0\mathrm{pp}$. On the basis of 215 events with known leptonic charge, we find for $x$, the ratio of the violating to nonviolating amplitude, $\mathrm{Re}x=0.12\mathrm{}\pm 0.09$ and $\mathrm{Im}x=-0.08\mathrm{}\pm 0.07$. Our result is consistent with no violation.

An exposure of the LRL 72-in. liquid-hydrogen bubble chamber to 6-BeV/c protons has yielded some 3000 examples of production of strange particles in four-body final states. Cross sections for the reactions $\mathrm{pp}\to \Lambda p{K}^0{\pi }^{+}$, $\mathrm{pp}\to \Lambda p{K}^{+}{\pi }^0$, and $\mathrm{pp}\to \Lambda n{K}^{+}{\pi }^{+}$ are 64±6 μb, and 43±4 μb, respectively. The resonances $K^{*}\mathrm{}\left(890\right)\mathrm{}$, $N^{*}\mathrm{}\left(1236\right)\mathrm{}$, and $Y^{*}\mathrm{}\left(1385\right)\mathrm{}$ are produced with cross sections $\sigma \left(p{K}^{*+}\right)=9\mathrm{}\pm 3$ μb, $\sigma \left({\Lambda }^0{\mathrm{K}}^0{N}^{*++}\right)=23\mathrm{}\pm 3$ μb, $\sigma \left(\Lambda K^{+}{N}^{*+}\right)=4\mathrm{}\pm 2$ μb, $\sigma \left(p{K}^0{Y}^{*+}\right)=11\mathrm{}\pm 2$ μb, $\sigma \left(p{K}^{+}{Y}^{*0\mathrm{}}\right)=7\mathrm{}\pm 1$ μb, and $\sigma \left(n{K}^{+}{Y}^{*+}\right)=15\mathrm{}\pm 2$ μb. Except for the low-$K\pi$-effective-mass region, the data are found to be in good agreement with a pion-exchange model.

This paper describes an experimental study of the decay parameters and the magnetic moment of the ${\Xi }^{-}$. A 1.8-GeV/c $K^{-}$ beam derived from the Bevatron was used to produce ${\Xi }^{-}$ by the reaction $K^{-}p\to {\Xi }^{-}{K}^{+}$. The $K^{+}$ and resulting decay products of the ${\Xi }^{-}$ were used to trigger a spark-chamber system, pictures from which yielded a total of 2724 events which passed all measuring criteria. The ${\Xi }^{-}$ were produced in an intense (170 kG) magnetic field obtained from a pulsed magnet. The precession of the magnetic moment of the ${\Xi }^{-}$ in the presence of this field can be measured from the angular distribution of the ${\Xi }^{-}$ decay products and a value of the magnetic moment obtained. The decay parameters and polarization of the ${\Xi }^{-}$ are also obtained from the angular distribution of the decay products; we obtain $\alpha =-0.383\mathrm{}\pm 0.065$, $\Phi =-(26\mathrm{}\pm 30)°$, and $\overline{P}=0.19\mathrm{}\pm 0.09$. The accuracy of the magnetic moment value is severely limited by the low value of polarization and experimental biases in the distribution; we obtain ${\mu }_{{\Xi }^{-}}=-0.1\mathrm{}\pm 2.1$ nuclear magnetons.

An experimental search for a bound (${\Sigma }^{-}n$) state produced an upper limit on the ${\pi }^{-}+d\to K^{+}+\left({\Sigma }^{-}n\right)$ cross section. For $P_{{\pi }^{-}\mathrm{lab}}=1.15\mathrm{}$ GeV/c, $25°\lesssim {\theta }_{K^{+}\mathrm{lab}}\lesssim 60°$, and an experimental width of ±10 MeV in the (${\Sigma }^{-}n$) mass, the result is $\sigma \le 0.16$ μb ${\mathrm{sr}}^{-1\mathrm{}}$, 90% confidence. This limit on the (${\Sigma }^{-}n$) production cross section is compared with the prediction of the Henley-Dante impulse model for (${\Sigma }^{-}n$) production; this comparison leads to an upper limit on the ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}\left({\Sigma }^{-}n\right)$ binding energy of 0.3 MeV, 90% confidence limit.

As a test of time-reversal invariance in electromagnetic interactions, a measurement was made of a $T$-invariance-forbidden polarization of the ${\Lambda }^0$ in the decay ${\Sigma }^0\to {\Lambda }^0+e^{+}+e^{-}$. The result of this experiment, combined with a previous measurement (also using stopping $K^{-}$ mesons in hydrogen bubble chambers as a source of ${\Sigma }^0$ hyperons), is a polarization of (3±6)%.

In the high-energy limit of $\mathrm{ee}$ elastic scattering, as given by all possible multiphoton exchanges, we have considered a large class of radiative corrections. This class of radiative corrections is one in which one ignores processes involving pair creations and anihilations. The resultant amplitude is found to be proportional to the square of the c.m. energy, multiplied by the product of the e.m. form factors and the eikonal form.

A divergenceless skew-symmetric second-order tensor field with a finite mass is considered. A Lagrangian is constructed. The quantization is performed for the free field, the propagator is obtained, and the relationship to the Proca field is discussed.

In the absence of vacuum polarization and under generalized soft-exchanged-photon approximations, which will be stated in the text, the leading behavior of charged-particle-scattering amplitudes are proportional to the square of the electromagnetic form factors, as conjectured by Wu and Yang, multiplied by the eikonal functions. This result includes radiative correction to all orders. It is further pointed out that it remains true in the presence of neutral scalars and pseudoscalars under the same approximation.

The relation between the original form of the Brans-Dicke (BD) theory and a particular form of the Jordan theory has been pointed out by Dicke. Here we establish the relation between the various unit-transformed BD theories and other Jordan theories. Although this formal identification is possible, the two theories are not equivalent, because of the different interpretations given to the matter Lagrangian and conservation laws in the various forms of the two theories.