Extension of the dispersive optical model to improve the description of high-momentum components

Abstract

An improved treatment of high-momentum components in nuclei is introduced in the framework of the dispersive optical model (DOM). The well-established feature that the peak of the spectral function appears at higher excitation energy in the $A$-1 system with increasing momentum has so far not been successfully accounted for in the DOM. To achieve this feature, it is necessary to abandon the factorization of energy dependence and geometry of the DOM self-energy. The volume absorption below the Fermi energy has thus been represented by a decreasing radius at larger missing energy implying that a numerical treatment of the dispersion relations is necessitated. Earlier DOM results for ${}^{48}$Ca are also improved with this approach, demonstrating that a small neutron skin can still be accompanied by protons having a larger high-momentum tail than neutrons.