Exotic baryon resonances in p + p interactions with the NA49 detector

Abstract

A search for baryon resonance states with exotic quantum numbers was performed in p+p interactions at 158 GeV beam energy with the large acceptance NA49 detector at the Cern SPS. A narrow Ξ−π− baryon resonance with mass of 1.862 ± 0.002 GeV/c2 and width below the detector resolution of ≈0.018 GeV/c2 is observed. This state is identified as a candidate for the hypothesized exotic Ξ−−5 baryon with and a quark content of . In the Ξ−π+ invariant mass spectrum at the same mass, an indication is observed of a candidate of the Ξ05 member of this isospin quartet with a quark content of . The corresponding antibaryon spectra show indications of enhancements at the same location.