Microscopic effects of the particle-vibration coupling on the photon emission in nucleon radiative capture

The form factor describing the particle-vibration coupling responsible for the excitation of giant electric multipole resonances in the semidirect contribution to fast nucleon radiative capture is expressed microscopically within the framework of the second quantization formalism in order to determine the influence of nuclear shell structure and two-body contributions on photon emission. Calculations performed for the 208Pb (n,γ) reaction reveal the limits of commonly used phenomenological approximations and give rise to some questions about the reliability of the latter approach, suggesting the need for an extensive and careful analysis in different mass regions. (orig.)