Mechanism of pion production in αp scattering at 1 GeV/nucleon

An analysis of the experimental data on one-pion and two-pion production in the p(α, α′)X reaction studied in a semi-exclusive experiment at an energy of E α = 4.2 GeV has been performed. The obtained results demonstrate that the inelastic α-particle scattering on the proton at the energy of the experiment proceeds either through excitation and decay of the Δ resonance in the projectile α particle, or through excitation in the target proton of the Roper resonance, which decays into a nucleon and a pion, or a nucleon and a σ meson—a system of two pions in the isospin I = 0, S-wave state.