We present a summary of the physics results from an experimental study of the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}n$ at 100 and 175 GeV/c incident-beam momentum. Our data show the continuing dominance of one-pion exchange in these reactions with the characteristic $\frac{1}{{{P}_{\mathrm{lab}}}^{2}}$ momentum dependence. We extract the pion Regge trajectory from our data on ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}n$ and study the zero structure of the $\ensuremath{\pi}\ensuremath{\pi}$ differential cross section up to ${s}_{\ensuremath{\pi}\ensuremath{\pi}}=12$ ${\mathrm{GeV}}^{2}$.

The reaction π−p → π+π−n was studied at 100 and 175 GeV/c incident beam momenta. The ϱ0 region cross section was 0.934 μb at 100 GeV/c and 0.229 μb at 175 GeV/c. Spherical harmonic moments in the Gottfried-Jackson frame are presented as a function of mass and proton-neutron four-momentum transfer. The pion Regge trajectory is calculated. Decay distributions are presented for the ϱ in the helicity and Gottfried-Jackson frames. The apparatus and analysis are discussed.

The reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}X$ has been studied at 50, 100, and 175 GeV/c. The observed $\mathrm{KK}\ensuremath{\pi}$ effective-mass spectrum is well described by a model assuming longitudinal phase space and two-body resonances. Production of resonances in $K\ensuremath{\pi}$ and $K\stackrel{-}{K}$ systems account for over 70% of the cross section. Estimated cross sections for $D(1285)$ and $E(1420)$ at 100 GeV/c are ${\ensuremath{\sigma}}_{D}B(D\ensuremath{\rightarrow}{K}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}})<0.1$ \ensuremath{\mu}b and ${\ensuremath{\sigma}}_{E}B(E\ensuremath{\rightarrow}{K}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}})=0.3\ifmmode\pm\else\textpm\fi{}0.2 $ \ensuremath{\mu}b. Results for the reaction ${K}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}X$ at 100 GeV/c are also presented.

The reaction ${K}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\overline{K}}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}p$ has been studied at 100 and 175 GeV/c and the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}^{0}{K}^{\ensuremath{-}}p$ at 50, 100, and 175 GeV/c. Both reactions are dominated by production of resonances, ${K}^{*}(890)$, ${K}^{*}(1430)$ and ${A}_{2}(1320)$, ${A}_{2}(2040)$, respectively. Production cross sections, $t$ distributions, and decay-angular distributions are studied. Isoscalar natural-parity exchange is dominant. The energy dependence of the ${K}^{*}$ and ${A}_{2}$ resonance production between 10 and 175 GeV/c is well described by a Regge-pole model. Our data on ${A}_{2}$ corrects that in an earlier paper.

High-transverse-energy events produced in proton-nucleus collisions at 400 GeV/c were studied with use of the Fermilab multiparticle spectrometer. The cross sections for such interactions increase more rapidly than the atomic mass number for both small- and large-acceptance data. The nuclear events are less planar than the corresponding high-transverse-energy $\mathrm{pp}$ events.

The reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}^{0}{K}^{\ensuremath{-}}p$ has been measured from 50 to 175 GeV/c. The production characteristics of the ${A}_{2}$ have been analyzed. We find spin and $t$ dependence similar to lower energies, but the cross section falls rapidly with energy. In a Regge description of ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{A}_{2}^{\ensuremath{-}}p$ our data imply a rather small Pomeron-exchange component.

Results are presented from the study of multikaon final states in the reactions r−p→K0K±r∓X̃, K0K+KX̃ at 50 and 100 GeV/c. Here X̃ is semi‐inclusive, because a specific forward topology and an interaction registering in the counters sourrounding the target are required. The D(1285) meson is seen in the dr mode, while the E(1420) meson is observed in both the dr and the KK modes. In addition, there are two possible enhancements in the three kaon final state. The first (M∠1840 MeV) is associated with the K0f mode and is consistent with being the charmed D0. The second, a K state (M = 2003±14 MeV, G = 87±43 MeV), decays into KA2.

We present results from the study of multikaon final states in the reactions ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}, {K}^{0}{K}^{+}{K}^{\ensuremath{-}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}$ at 50 and 100 GeV/c. Here $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}$ is semi-inclusive, that is, a specific forward topology and an interaction registering in the counters surrounding the target are required. The $D(1285)$ meson is seen in the $\ensuremath{\delta}\ensuremath{\pi}$ mode, while the $E(1420)$ meson is observed in both the $\ensuremath{\delta}\ensuremath{\pi}$ and the ${K}^{*}K$ modes. In addition, there are two possible enhancements in the three-kaon final state. The first ($M\ensuremath{\sim}1840$ MeV) is associated with the ${K}^{0}\ensuremath{\varphi}$ mode and is consistent with being the charmed ${D}^{0}$. The second, a ${K}^{*}$ state ($M=2003\ifmmode\pm\else\textpm\fi{}14$ MeV, $\ensuremath{\Gamma}=87\ifmmode\pm\else\textpm\fi{}43$ MeV), decays into $K{A}_{2}$.

${K}^{+}p$ and ${K}^{+}d$ total cross sections were measured in the momentum range 0.57-1.16 GeV/c using a secondary, separated kaon beam of the Lawrence Berkeley Laboratory Bevatron and conventional transmission-counter techniques. No evidence was found for structure in the cross section of either reaction as previously indicated near 0.7 GeV/c.

Total cross sections for ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\Lambda}{K}^{0}$ have been measured using optical spark chambers from threshold to $1.13\ensuremath{-}\frac{\mathrm{GeV}}{c}$ beam momentum in $19\ensuremath{-}\frac{\mathrm{MeV}}{c}$ intervals, but with a $1\ensuremath{-}\frac{\mathrm{MeV}}{c}$ resolution in the regions of the $\ensuremath{\Lambda}K$ and $\ensuremath{\Sigma}K$ thresholds. The behavior near $\ensuremath{\Lambda}K$ threshold indicates a significant $s$-wave contribution, but this experiment is unable to resolve any cusplike behavior in the region of the $\ensuremath{\Sigma}K$ thresholds. The cross section shows a broad peak in the vicinity of $1.05\ensuremath{-}\frac{\mathrm{GeV}}{\mathbf{c}}$ beam momentum.