Isospin dependent nucleon-nucleus optical potential with Skyrme interactions

Abstract

In this paper, the isospin dependent nucleon-nucleus optical potential theory is introduced on the basis of the effective Skyrme interactions. From the view of the many-body theory, the nucleon optical potential can be identified with the mass operator of the one-particle Green function. The first and second order mass operators of the one particle Green function in nuclear matter are derived, and the real and imaginary parts of the optical potential for finite nuclei are obtained as usual by applying a local density approximation. Our results, in most cases, can be derived and expressed analytically. From an extensive comparison with experimental data of various quantities of interests, it is concluded that for certain versions of Skyrme interactions without parameter adjusting the agreement between theory and experiments can be obtained satisfactorily. We define the ratio of the difference and summation of the neutron and proton nonelastic cross sections as the isospin effect value. The calculated results show that the isopin effect value decreases as the incident energy increases and increases as the asymmetric parameter α 0 = (N -Z)/A of the target nucleus increases.

Microscopic optical potential for exotic isotopes from chiral effective field theory

“…The isovector contribution to the optical potential, arising from π-meson exchange and ρ-meson exchange in traditional one-boson exchange models, has a stronger relative energy dependence. In the past, semimicroscopic and microscopic optical potentials have been constructed from mean field theory [25][26][27] and realistic nucleon-nucleon interactions [28][29][30][31][32][33] respectively, and there is significant disagreement regarding the energy dependence of the isovector components. To date there are therefore no strong constraints on the kinematic transition region associated with isospin inversion.…”

The nucleon microscopic optical potential based on the Skyrme interaction

“…The real and imaginary parts of the MOP for finite nuclei are obtained by applying a local density approximation [3]. Using certain versions of the Skyrme interactions we have obtained the microscopic optical potential [4] for finite nuclei which showed that the potential depth, shape, relative contributions of the surface and volume parts, as well as the energy dependence are in reasonable agreement with the phenomenological optical potentials and those based on realistic nuclear force for certain energy regions.…”

“…If the t 4 and t 5 are zero, the expression of Eq. (7) is the so-called conventional Skyrme interaction [4,5].…”

“…Based on the conventional and extended Skyrme interaction parameters, the real and imaginary parts of nucleon MOP can be achieved and the detailed description can be found in Refs. [4,5].…”

“…As in the approach used in Refs. [4,6,7], the nuclear densities are similarly expressed by the Negele's empirical formula [8].…”