Universal separable structure of the optical potential

TL;DR

This paper uncovers a universal, microscopic structure of the optical potential in nuclear physics, highlighting its complex nonlocality and radial features across a broad energy and mass range, challenging traditional models.

Contribution

It introduces a microscopic, universal separable form of the optical potential, revealing complex nonlocality and a nodal point in the imaginary component, advancing nuclear reaction modeling.

Findings

Nonlocality form factor is inherently complex and hydrogenic.

Nodal point in the imaginary radial form factor suppresses surface absorption.

Radial form factor can be represented as convolutions of spherical, Gaussian, and Yukawa functions.

Abstract

Based on a momentum-space in-medium folding model, we disclose the universal separability of the optical potential, revealing its radial and nonlocality features at beam energies in the range 40 - 400 MeV and target mass numbers in the range $40\le A\le 208$. From this microscopic study we find that the nonlocality form factor is inherently complex and of hydrogenic nature, affecting both central and spin-orbit components of the potential. A striking outcome from this study is the consistent appearance of a nodal point in the imaginary radial form factor, notably suppressing surface absorption peaks, in evident contrast with Woods-Saxon's assumption of an absorptive peak at the nuclear surface. Our analysis reveals that the complex radial form factor can effectively be represented as convolutions of uniform spherical distribution with a Gaussian form factor and a Yukawa term. These robust microscopically-driven findings offer new ways for investigating nuclear reactions beyond the restricting Woods-Saxon and Perey-Buck assumptions.