Implications of Energy-Dependent Nonlocality in the Optical Model for Nucleon Scattering at Intermediate Energies

The optical model potential for intermediate-energy nucleon-nucleus scattering (≈ 10–200 MeV) exhibits a significant energy dependence in both the real and imaginary components. The Perey-Buck model associates the local potentials depending on the energy with the non-local Gaussian potentials [F. Perey and B. Buck, Nucl. Phys. 32, 353–380 (1962)]. Still, the microscopic methods show that the imaginary part still has energy dependence due to the real temporal non-locality and the channel couplings among them. The present work mainly considers the energy-dependent nonlocality and thus the extension of semimicroscopic approaches. The real part is obtained through the single-folding of the M3Y-Paris interaction, which is density-dependent, while the imaginary part is phenomenological and includes coupled-channels effects. A range of energy-dependent nonlocality β(E) is introduced, and the results are contrasted with the experimental data from EXFOR for elastic scattering of neutrons and protons by nuclei from ¹²C to ²⁰⁸Pb. The findings indicate that differential cross sections and analyzing powers have been fitted much better, particularly in the backscattering areas; thus, the introduction of energy-dependent non-locality is necessary to explain the dispersive corrections and Pauli effects.