Do proton-neutron pairs behave like quasideuterons in the photoabsorption process?

Calculations have been performed for the ¹⁶O(γ,pn) reaction in the photon-energy range E_γ=50–300MeV. Effects due to both one-pion exchange currents and the Δ have been included. We discriminate between different couplings of the initial proton-neutron (pn) pair involved in the reaction. At lower photon energies where the pion exchange currents dominate the cross section it is found that pn pairs in the finite nucleus do not fully behave like a quasideuteron. Therefore, we feel that the factorized form of the (γ,pn) cross section should be used with reservation.