Total and annihilation cross sections for $\overline{p}p$ and $\overline{p}d$ have been measured over the momentum range 355-1066 MeV/c at closely spaced momenta and with good energy resolution. No evidence is seen for the narrow structure reported by other experiments in the vicinity of 500 MeV/c. The present measurements indicate a broader enhancement in this region, which, if interpreted as a resonance, would have a height of ∼ 3 mb and a width of ∼ 20 MeV. This structure appears only in the $\overline{p}p$ data.

• Received 9 January 1980

DOI:https://doi.org/10.1103/PhysRevLett.44.1182