We report a measurement of the missing mass ($\mathrm{MM}$) spectra from the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{(\mathrm{MM})}^{\ensuremath{-}}+p$ at 11, 13.4, and 16 GeV, in the region of the $S(1930)$, $T(2200)$, and $U(2375)$ mesons. Our mass spectra exhibit no narrow enhancements in this region with $〈\frac{d\ensuremath{\sigma}}{\mathrm{dt}〉}\ensuremath{\gtrsim}10$ \ensuremath{\mu}b/Ge${\mathrm{V}}^{2}$.

We have measured, by the missing-mass technique, spectra of the neutral-meson system ${X}^{0}$ produced in ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p{X}^{0}$ at 13.4 GeV/c. The ${\ensuremath{\pi}}^{0}$, ${\ensuremath{\rho}}^{0}$, and ${\ensuremath{\omega}}^{0}$ appear as well as a broad enhancement at 450 MeV and a narrow peak at 1280 MeV which is interpreted as the ${D}^{0}$. Most of the ${\ensuremath{\pi}}^{0}$ signal and the events around 450 MeV are correlated with ${N}^{*+}$ production. The ${\ensuremath{\rho}}^{0}$ peak results primarily from ${{A}_{1}}^{\ensuremath{-}}\ensuremath{-}{{A}_{2}}^{\ensuremath{-}}$ decays. We find, however, that the ${\ensuremath{\omega}}^{0}$ and ${D}^{0}$ are largely uncorrelated with ${N}^{*+}$ or ${X}^{\ensuremath{-}}$ resonances.

Measurements of missing mass (MM) spectra from π−p ⇒ (MM)−p at 8, 11, 13.5, and 16 GeV are reported. The MM mass range examined is 0 ≤ M2 ≤ 7.3 GeV2 with t (the proton four momentum transfer squared) in the interval 0.2 ≤ ∣t∣ ≤ 0.3 GeV2. Narrow resonances (R1, R2, R3, S, T, and U) with cross sections and widths reported by the CERN missing mass group are ruled out by the data. The cross sections d2σ/dtdM2 show evidence for triple factorizability of the form d2σdtdM2 ≃ D(PB)A(M2)G(P⊥2) where PB is the incident beam momentum,and P⊥2 is the perpendicular component of the detected proton's momentum with respect to the beam direction.

We have measured, by the missing-mass technique, spectra of the neutral-meson system ${X}^{0}$ produced in ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p{X}^{0}$ at 13.4 GeV/c. The ${\ensuremath{\pi}}^{0}$, ${\ensuremath{\rho}}^{0}$, and ${\ensuremath{\omega}}^{0}$ appear as well as a broad enhancement at 450 MeV and a narrow peak at 1280 MeV which is interpreted as the ${D}^{0}$. Most of the ${\ensuremath{\pi}}^{0}$ signal and the events around 450 MeV are correlated with ${N}^{*+}$ production. The ${\ensuremath{\rho}}^{0}$ peak results primarily from ${{A}_{1}}^{\ensuremath{-}}\ensuremath{-}{{A}_{2}}^{\ensuremath{-}}$ decays. We find, however, that the ${\ensuremath{\omega}}^{0}$ and ${D}^{0}$ are largely uncorrelated with ${N}^{*+}$ or ${X}^{\ensuremath{-}}$ resonances.

We report on a measurement of the missing-mass, ${(\mathrm{mm})}^{\ensuremath{-}}$, spectrum from the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{(\mathrm{mm})}^{\ensuremath{-}}+p$ at 8 GeV. The data contain 6500 events in the $R$ peak (${M}^{2}=2.72\ifmmode\pm\else\textpm\fi{}0.02$ Ge${\mathrm{V}}^{2}$, $\ensuremath{\Gamma}=139\ifmmode\pm\else\textpm\fi{}31$ MeV). The $R$ shape is consistent with either a single Breit-Wigner or several wide resonances, as suggested by bubble-chamber experiments, but inconsistent with the series of narrow resonances reported by the CERN missing-mass group.

Observations of the mass distribution of the ${A}_{2}$ meson produced in the reaction $\ensuremath{\pi}p\ensuremath{\rightarrow}{A}_{2}p$ are reported. The ${A}_{2}$'s were observed using a missing-mass technique. Measurements were made with 5- and 7-GeV ${\ensuremath{\pi}}^{\ensuremath{-}}$ as well as 5-GeV ${\ensuremath{\pi}}^{+}$ beams. For each beam setting more than 17000 ${A}_{2}$'s above background were observed with $0.20<~|t|<~0.29$ Ge${\mathrm{V}}^{2}$. The ${A}_{2}$ peaks are well described by a Breit-Wigner shape, whereas the dipole mass formula does not fit the data.