Double Δ production in the γd → pnπ+π− reaction

We have studied the γd → Δ++Δ− reaction which requires the collaboration of the two nucleons in deuteron. By means of a model previously developed for the γp → pπ+π− reaction, the two-body exchange currents leading to double delta creation are derived. A fair agreement is obtained with a recent experiment, but more precise measurements and the extension to higher photon energies look advisable in order to see the limits of the present theoretical approach.