We show that the inclusion of correlation effects in describing the nuclear photoabsorption cross section via the excitation of a collective mode leads to a Breit-Wigner type curve with energy dependent width. We also show that a very slow energy dependence is enough to reproduce the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ data up to ∼139 MeV, turning a quantitative assignment of the quasi-deuteron contribution, a rather delicate matter.

• Received 12 February 1987

DOI:https://doi.org/10.1103/PhysRevC.35.2341