The role of Δ(1700) excitation and ρ production in double pion photoproduction Original Research Article

Recent information on invariant mass distributions of the γp→π+π0n reaction, where previous theoretical models had shown deficiencies, have made more evident the need for new mechanisms, so far neglected or inaccurately included. We have updated a previous model to include new necessary mechanisms. We find that the production of the ρ meson, and the Δ(1700) excitation, through interference with the dominant terms, are important mechanisms that solve the puzzle of the γp→π+π0n reaction without spoiling the early agreement with the γp→π+π−p and γp→π0π0p reactions.