Search for Narrow Resonances in theRRegion

Abstract

We report on a measurement of the missing-mass, ${\mathrm{}\left(\mathrm{mm}\right)\mathrm{}}^{-}$, spectrum from the reaction ${\pi }^{-}+p\to {\mathrm{}\left(\mathrm{mm}\right)\mathrm{}}^{-}+p$ at 8 GeV. The data contain 6500 events in the $R$ peak ($M^2=2.72\mathrm{}\pm 0.02$ Ge${\mathrm{V}}^2$, $\Gamma =139\mathrm{}\pm 31$ 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.