We report on observation of the isospin-½ ${\Xi }^{*}\mathrm{}\left(1530\right)\mathrm{}$ and ${\Xi }^{*}\mathrm{}\left(1830\right)\mathrm{}$ resonances in $K^{-}n$ interactions at 3.6 and 3.9 GeV/c and present results concerning the production and subsequent decay of the ${\Xi }^{*}\mathrm{}\left(1830\right)\mathrm{}$ into $\Xi \pi$, $\Xi \pi \pi$, and $\Lambda \overline{K}$. We have also searched for isospin-$\frac{3}{2}$ ${\Xi }^{*}$ resonances and found no strong evidence for the existence of such states. Upper limits on production cross sections for such a particle are presented.

Prominent features of this reaction include $d^{*}$ production in the $d{\pi }^{+}$ system, ${\rho }^0$ production, and a low-mass enhancement ($A_1$) in the ${\rho }^0{\pi }^{+}$ system. A model for $\pi d$ scattering has been found to provide an adequate description of the properties of the $d^{*}$. A Reggeized pion-exchange model successfully predicts the properties of the ${\rho }^0{\pi }^{+}d$ final state, whether or not $d^{*}$ formation occurs.

A large-area (3.35 ${\mathrm{m}}^2$) scintillation-counter telescope consisting of six scintillation counters and four widegap spark chambers was arranged to detect single particles with charge $\pm \frac{1}{3}e$ or $\pm \frac{2}{3}e$ which might be present in the cosmic radiation near sea level. Upper limits to the vertical intensities of such particles are 9.8×${10}^{-11\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ for charge $\pm \frac{1}{3}e$ and 1.6×${10}^{-10\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ for charge $\pm \frac{2}{3}e$ at a 90% confidence level.

We have extended our earlier measurements of the cross section for wide-angle electron bremsstrahlung. Besides the data for symmetric final electron and photon angles already published, we report results for asymmetric angles. The circulating electron beam of the Cornell 10-GeV synchrotron struck a carbon target and was monitored by observing the forward bremsstrahlung beam. Wide-angle photons were counted in coincidence with the corresponding scattered electrons. The recoil momentum of the unobserved nucleus was minimized. The experimental cross sections are compared with the predictions of the Bethe-Heitler formula corrected for elastic and inelastic nuclear form factors and for virtual nuclear Compton scattering. The agreement is excellent, confirming the predictions of quantum electrodynamics for timelike electron four-momenta up to 1.2 GeV. If one assumes a deviation in the experiment/theory ratio proportional to the square of the final electron-photon invariant mass, the 95% confidence upper limit on the corresponding distance parameter is ${{\Lambda }_{\mathrm{}\left(2\right)\mathrm{}}}^{-1\mathrm{}}=5.3\mathrm{}\times {10}^{-15\mathrm{}}$ cm. The upper limit for a fourth-power deviation is ${{\Lambda }_{\mathrm{}\left(4\right)\mathrm{}}}^{-1\mathrm{}}=6.2\mathrm{}\times {10}^{-15\mathrm{}}$ cm.

The elastic muon-electron interactions of 10.1-GeV/c positive and 5.0- and 14.5-GeV/c negative muons produced at the Brookhaven alternating gradient synchrotron have been studied in nuclear emulsions. Energies of knockon electrons calculated from scattering measurements were compared with those obtained from their ejection angles. Integral cross sections were compared with the Bhabha prediction for the scattering of two point fermions. Excellent agreement was found for negative and positive primary muons up to $t=3.3\mathrm{}\times {10}^{-3\mathrm{}}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and $t=1.8\mathrm{}\times {10}^{-3\mathrm{}}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$, respectively. Our results are in contradiction to some of the previous cosmic-ray data, which show an anomalously large cross section.

The SLAC 2.2-m streamer chamber has been used to study photoproduction from hydrogen with a 16-GeV bremsstrahlung beam. The use of a single-hadron trigger permitted a study from 2 to 16 GeV which included photoproduction of the ${\Delta }^{++}$ and of the vector mesons $\rho$, $\omega$, and $\phi$. The sample reported here represents 87 000 pictures containing 7055 hadronic events of which about 2500 were above 5 GeV. Interesting aspects of the data are the dominance of ${\rho }^0$ production in the three-prong topology at high energies, the diffraction character of high-energy ${\rho }^0$ production, the clear indication of the transversality of the ${\rho }^0$ spin orientation, and the apparent interference between the resonant ${\pi }^{+}{\pi }^{-}$ (${\rho }^0$) production and a nonresonant background. Tests of the vector-dominance model are described, including a comparison of total photo-production cross sections derived from our data with those obtained elsewhere by direct measurements.

We have analyzed approximately 9000 four-prong events produced by ${\pi }^{-}p$ interactions at 6.7 GeV/c. All the effective-mass distributions from final states ${\pi }^{-}{\pi }^{-}{\pi }^{+}p$, ${\pi }^{-}{\pi }^{-}{\pi }^{+}{\pi }^{0}p$, and ${\pi }^{-}{\pi }^{-}{\pi }^{+}{\pi }^{+}n$ are presented, as well as cross sections. Resonances in each final state amount to more than 50% of total events, dominated by $\rho$ mesons and $\Delta \mathrm{}\left(1236\right)\mathrm{}$ baryons. Three-pion mass distributions show strong signals in the $A$-meson region in all three final states, but only a modest enhancement is observed in the $R$-meson region. We rule out $J^P$ of $0^{-}$ and $2^{+}$ for the $A_{1.5}$. A similar analysis for the $A_1$ is consistent with $1^{+}$. In the $\pi \rho$ and $\pi \eta$ mass distributions no evidence for $A_2$ structure is seen. Low-mass enhancements in four-pion mass distributions appear in the region of the $B$ meson and the $\rho \mathrm{}\left(1700\right)\mathrm{}$ meson. There is also possibly some evidence for $f^{\prime }\to 4\pi$. Higher-mass nucleon isobars are found to be closely associated with $\Delta \mathrm{}\left(1236\right)\mathrm{}$ production. There is no significant production of quasi-two-body final states.

An experiment has been carried out to search for uncharged particles with spacelike four-momentum which presumably travel faster than light. No evidence for such particles has been found. The results can be expressed as upper limits on the production rates for such particles by stopped $K^{-}$ and $\overline{p}$ compared to production rates of pions in similar reactions: $\frac{(K^{-}+p\to {\Lambda }^0+t^0)}{(K^{-}+p\to {\Lambda }^0+{\pi }^0)}\le 2\times {10}^{-3\mathrm{}}$, $\frac{(K^{-}+p\to {\Lambda }^0+t^0+{\overline{t}}^0)}{(K^{-}+p\to {\Lambda }^0+{\pi }^0)}\le 2.5\times {10}^{-3\mathrm{}}$, $\frac{(\overline{p}+p\to {\pi }^{+}+{\pi }^{-}+t^0)}{(\overline{p}+p\to 3\pi )}\le 2\times {10}^{-3\mathrm{}}$, $\frac{(\overline{p}+p\to {\pi }^{+}+{\pi }^{-}+t^0+{\overline{t}}^0)}{(\overline{p}+p\to 4\pi )}\le 1\times {10}^{-3\mathrm{}}$. Other sources of information placing limits on the interactions of tachyons are discussed.

The polarization and the differential cross section in ${\pi }^{-}p$ elastic scattering have been measured at incident pion laboratory momenta of 1.70, 1.88, 2.07, 2.27, and 2.50 GeV/c. The experiment was carried out at the Argonne zero-gradient synchrotron with a polarized proton target. Details of the apparatus and data analysis are presented here together with the final results. A partial-wave analysis of the data has verified the $J^P=\frac{7}{2^{+}}$ assignment for the $\Delta \mathrm{}\left(1950\right)\mathrm{}$ and established a $J^P=\frac{7}{2^{-}}$ assignment for the $N\left(2190\right)\mathrm{}$. It does not support a $J^P=\frac{11}{2^{+}}$ assignment for the $\Delta \mathrm{}\left(2460\right)\mathrm{}$, nor does it give support for some of the possible resonances found in the CERN phase-shift analysis. Apart from the resonance behavior, the partial-wave analysis reveals several new features. We find a striking correlation among the various partial-wave amplitudes at the highest energy, which is different for $J=l+\frac{1}{2}$ and $J=l-\frac{1}{2}$. In addition, several fixed-($-t$) features of high-energy scattering emerge in the energy region of this analysis.

Planar duality amplitudes are shown to have Regge asymptotic behavior when $\mathrm{}\left|s\right|\mathrm{}\to \infty$ at any non-vanishing angle to the real axis with $t$ fixed. The asymptotic behavior of the amplitudes in the same $s$ limit with $u$ fixed is also investigated.

The effect of the annihilation of nucleon-antinucleon pairs upon the process of matter-antimatter separation in blackbody radiation is considered. It is shown to be negligible if annihilation is correctly described by the statistical model.

Weinberg's approach to the high-energy behavior of chiral Lagrangians is applied to the process $\pi +\alpha \to 2\pi +\beta$, and it is shown that the algebraic relations required to give good asymptotic behavior in this process are the same as those which give good behavior in the reaction $\pi +\alpha \to \pi +\beta$.

Pfleegor and Mandel produced interference effects from two separate independent laser beams when the quanta arriving at the detector were separated in time by an average of about 1.4×${10}^{-7\mathrm{}}$ sec. If the quanta are photons (particles), then, to produce interference, each photon must store energy in the detector for an average of at least 1.4×${10}^{-7\mathrm{}}$ sec. But Jánossy and Náray have recently shown that over a period of 9×${10}^{-9\mathrm{}}$ sec there is no such storage, at least when the phases are random. Thus the result of Pfleegor and Mandel is in conflict with the corpuscular concept of visible light.

The kernel needed in the application of the unitarity condition in the Blankenbecler-Goldberger impact-parameter representation is reduced to a simple sum suitable for numerical work. We also comment briefly on a modified version of the representation.

We present a theory of the origin of the weak-interaction angle $\theta$, based on a self-consistency condition linking weak, strong, and electromagnetic symmetry-breaking effects. The value of $\theta$ is related to the observed pattern of breaking of $\mathrm{SU}\left(3\right)\mathrm{}\otimes \mathrm{SU}\left(3\right)\mathrm{}$, and depends upon the value of a new parameter $\xi$, which gives the strength of the weak corrections to strong processes. A characteristic result of the theory is the prediction of a nonelectromagnetic isospin breaking. This solves the $\eta \to 3\pi$ puzzle and accounts for the observed deviation from the Dashen sum rule: ${m_K}^{+2\mathrm{}}-{m_K}^{02}={m_{\pi }}^{+2\mathrm{}}-{m_{\pi }}^{02}$. Although we are not able to give a theoretical evaluation of $\xi$ in a realistic model of weak interactions, a phenomenological determination of $\xi$ is proposed, based on the observed isospin-breaking mass splittings among pseudoscalar mesons. In this way we get the prediction $\theta \approx 0.25$, which is in good agreement with the experimental value.

We construct a model of the Veneziano type for $\pi A_1$ elastic scattering. We find that the imposition of factorization determines the model almost completely in terms of models for $\pi \pi \to \pi \pi$ and $\pi \pi \to \pi A_1$; and that the mere existence of a model for $\pi A_1\to \pi A_1$ constrains the model for $\pi \pi \to \pi A_1$. An off-shell continuation of the model consistent with the hard-pion formalism is given. The combination of this continuation with the constraint mentioned above ensures that the "constants" multiplying the Veneziano functions must depend explicitly on the four-momentum squared of the particle off the mass shell; and that the Adler consistency condition is satisfied by the vanishing of these constants at zero four-momentum rather than by a condition on the trajectory function or the external masses.

Using the multiperipheral integral equation in a factorizable approximation, we construct a simple model in which Regge poles and cuts can be studied. In a one-pole version of this model, we obtain a bootstrap of a Regge trajectory and residue function. In a two-pole version, we study the Pomeranchuk singularity for small $t$, and its relation to the Amati-Fubini-Stanghellini cut.

The $K_{l3\mathrm{}}$-decay form factors $f_{\pm }\mathrm{}\left(t\right)\mathrm{}$ are discussed from a phenomenological Lagrangian approach based on the notions of chiral dynamics and field-current identity. For the spin-zero fields, a real $\sigma$ model in $\mathrm{SU}\left(3\right)\mathrm{}\otimes \mathrm{SU}\left(3\right)\mathrm{}$ is considered. The vector and axial-vector fields are introduced as gauge fields in this model, which then preserves the concept of field-current identity. The model has been made general so that one can study the possibility of both the kinetic-energy-mixing and the mass-mixing models for the massive gauge fields. It is found that the strong vector-meson decays $\rho \to \pi \pi$ and $K^{*}\to K\pi$ and the weak $K_{l3\mathrm{}}$ decays form a consistent picture in this model. For comaprison with experiments, expressions of experimentally measurable quantities are first derived for the general case of simultaneous mass and kinetic-energy mixing. The results for these kinds of gauge-field model are then studied separately. It is found that the Glashow-Weinberg relation for $f_{+}\mathrm{}\left(0\right)\mathrm{}$ should be exact up to second order in symmetry breaking for a gauge-field model where the symmetry breaking is manifested only through changes in the kinetic-energy matrix $Z$ and the mass matrix $M$. Expressions for the corrections to the $K_{l3\mathrm{}}$ form factors due to the existence of the scalar mesons are derived. In the limit of the nonexistent $\kappa$ meson (i.e., $m_s\to \infty$ and $f_s\to 0$), all the results reduce to those of Lee. Some discrepancies between the present work and the work of other authors using the current-algebra techniques are discussed.

A convenient method is introduced to analyze the requirements imposed by the analyticity of the full helicity amplitudes on the structure of Regge poles and their residues at $t=0\mathrm{}$ for two-body-to-two-body reactions with general masses and spins. This method enables us to visualize the structure of daughter trajectories and conspirators clearly. Also, in practice, this method enables us to make the following derivation easily for reactions with arbitrary spins. (1) The most singular parts of the daughter and conspirator residues at $t=0\mathrm{}$ are calculated for unequal-mass-unequal-mass reactions and unequal-mass-unequal-mass reactions. Then, through factorization, the nonvanishing parts of the daughter and conspirator residues are obtained for the equal-mass-equal-mass reactions. They are identified with a one-Lorentz-pole expansion. (2) In calculating the daughter and conspirator residues, the analyticity requirements of both the $t$-channel and the $s$-channel helicity amplitudes are satisfied. Therefore, the conspiracy equations are shown to be satisfied explicitly. (3) The restrictions on the slopes of the daughter trajectories are also obtained. Their independence of the external masses and spins is shown. (4) The restrictions on the slopes of the conspirators are also calculated. We obtain an interesting new result: For a trajectory of quantum number $M$, at $t=0\mathrm{}$, the trajectories ${\alpha }_{+}\mathrm{}\left(t\right)\mathrm{}$ and ${\alpha }_{-}\mathrm{}\left(t\right)\mathrm{}$ are equal, and likewise their derivatives up to the $\mathrm{}(M-1\mathrm{})\mathrm{}\mathrm{th}$. Before carrying out all these calculations, all the $t$ factors of the Regge residue have to be determined. By introducing a quantum number $M$ in the unequal-mass-unequal-mass reactions, the $t$ factors of the parent as well as the daughter residues are uniquely determined using the conventional method of analyticity and factorization. This quantum number $M$ is identified to be the $O\left(4\right)\mathrm{}$ $M$ in the equal-mass-equal-mass reactions. We note that if the definition of the quantum number $M$ is not affected by the coincidence of $\alpha \mathrm{}\left(t\right)\mathrm{}$ with an integer at $t=0\mathrm{}$, then the trajectory $\alpha \mathrm{}\left(0\right)\mathrm{}$ will choose sense if $M<\mathrm{}\alpha \mathrm{}\left(0\right)\mathrm{}$ and choose nonsense if $M>\mathrm{}\alpha \mathrm{}\left(0\right)\mathrm{}$. At the end of the paper, a discussion is given on the implications for the group-theoretical approach to the Regge-pole theory.

Necessary and sufficient conditions for baryon spectral-function sum rules are obtained under the assumptions that (1) the equal-time commutator of the axial charges ${Q_5}^a\left(x_0\right)$ ($a=1, 2, 3$) and the nucleon field $\overline{\psi }\mathrm{}\left(y\right)\mathrm{}$ is given by $\left[{Q_5}^a\right(y_0), \overline{\psi }\mathrm{}(y\left)\right]=-r_A\overline{\psi }\mathrm{}\left(y\right)\mathrm{}{\gamma }_5{\tau }^a+(\Delta I=\frac{3}{2} \mathrm{terms})$ and that (2) the axial-vector current ${A_{\mu }}^a\mathrm{}\left(x\right)\mathrm{}$ is conserved. For each of these sum rules (enumerated by $n=1, 2, 3\dots$), the equivalence to $\int d^{3}z{〈{\left[{Q_5}^a\right(y_0), {\left[{\left(\frac{\partial }{\partial y_0}\right)}^{2n-1}\psi \mathrm{}\right(y), \overline{\psi }\mathrm{}(z\left)\right]}_{+}]|}_{y_0=z_0}〉}_0=0\mathrm{}$ is actually shown under weaker conditions: assumption (1) and, instead of (2), ${{\Sigma }_{j=0\mathrm{}}}^{2n-2}{〈{{\left[\right\{{\left(\frac{\partial }{\partial y_0}\right)}^j[\int d^{3}x{\partial }^{\mu }{A_{\mu }}^a\left(y_0\mathrm{x}\right), {\left(\frac{\partial }{\partial y_0}\right)}^{2n-2-j}\psi \mathrm{}(y\left)\right]\}, \psi \mathrm{}(z\left)\right]}_{+}|}_{y_0=z_0}〉}_0=0\mathrm{}$. Further equivalences are given. The sum rules connect the ($I=\frac{1}{2}$, $J={\frac{1}{2}}^{+}$) and ($I=\frac{1}{2}$, $J={\frac{1}{2}}^{-}$) baryon spectrum and include (for $n=1\mathrm{}$) a sum rule, obtained independently by Rothleitner and (in the one-particle approximation) by Sugawara. In our derivation we make no assumptions on high-energy behavior and we use an identity of the Jacobi type. Assuming the first two sum rules to be valid, the model then predicts a $P_{11}(m>\mathrm{}1470\mathrm{} \mathrm{MeV})$ resonance [which may be identified as the observed $P_{11}\mathrm{}\left(1750\right)\mathrm{}$] from the existence of the four nucleon resonances $P_{11}\mathrm{}\left(940\right)\mathrm{}$, $P_{11}\mathrm{}\left(1470\right)\mathrm{}$, $S_{11}\mathrm{}\left(1550\right)\mathrm{}$, and $S_{11}\mathrm{}\left(1710\right)\mathrm{}$.