A model for the mass-number independence of the antiproton annihilation on nuclei at low energies

A simple model explaining the recently observed approximate independence of the annihilation cross section on light nuclei at low energies is proposed. The salient idea is based on the realization that the πs from the annihilation on a nucleon have energies in the region of the Δ(1232) resonance. The coherent propagation of these πs through the excitation of several Δ resonances results in a destructive interference explaining why the annihilation of antiprotons in nuclei is suppressed. This model suggests a very effective way to produce “Δ matter” with several Δ resonances in interaction.