Evidence for ηη resonances in antiproton-proton annihilations at 2950 < s < 3620 MeV

Abstract We present the first high-statistics study of the ηη system over the mass range 1000–3000 MeV/ c 2 . The experiment was performed at the Fermilab Antiproton Accumulator, and the data sample consists of six-photon final states produced in antiproton-proton annihilations at s in the range 2950–3620 MeV. We find evidence for three states with masses 1488 ± 10 MeV/ c 2 , 1748 ± 10 MeV/ c 2 and 2104 ± 20 MeV/ c 2 respectively.