Observation of a Narrow Antibaryon State at 2.26GeV/c2

We report evidence, from a study of multihadron final states produced in the wide-band photon beam at Fermilab, for the production of a new antibaryon state which decays into $\overline{\ensuremath{\Lambda}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$. The mass of this state is 2.26 \ifmmode\pm\else\textpm\fi{} 0.01 ${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c}}^{2}$ and its decay width is less than 75 ${\mathrm{M}\mathrm{e}\mathrm{V}/\mathit{c}}^{2}$. We also report evidence of a state of higher mass (\ensuremath{\sim}2.5 ${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c}}^{2}$) which decays into the state at 2.26 ${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c}}^{2}$.