Abstract: 

The Gogny interaction was established by D. Gogny forty years ago [1] aimed to describe simultaneously the mean  eld and the pairing  eld with the same interaction. This type of forces consists of a finite-range part and a zero-range density dependent term together with a spin-orbit interaction, which is also of zero-range. The finite-range contribution consists of the sum of two Gaussian form-factors of different ranges, which simulate the short- and long-range parts of the interaction. The Gogny force D1S [2] have been used in large-scale Hartree-Fock-Bogoliubov calculations along the whole periodic table [3]. This force, as well as the improved parametrizations D1N [4] and D1M [5], are, actually, benchmarks of the deformation and pairing properties of the ground-state of finite nuclei.

The Gogny forces are effective interactions and therefore extrapolations to different scenarios from the one where the forces were fitted is not evident a priori and shall be carefully checked. In this talk, I will review the extrapolation of Gogny forces to describe neutron stars and nucleon-nucleus elastic scattering. The standard Gogny forces of the D1 family, namely D1S, D1N and D1M, suffer of too soft symmetry energy and fail in predicting the maximum mass of two solar masses (2M⦿), as required by recent astronomical observations. To overcome these limitations, we have proposed a reparametrization of the Gogny D1M force by increasing the slope of the symmetry energy, and therefore reaching the maximum mass of 2M⦿, and at the same time, providing a description of  finite nuclei with a global quality similar to that found using the original D1M force. This new force, named D1M, has been used to build up a global Equation of State from the outer crust to the core, able to reproduce the physics of neutron stars reasonably well as has been reported recently in a review article [6].

The application of Gogny forces to nuclear reactions has been discussed in a recent paper [7]. We have obtained the optical potential in a semi-microscopic nuclear matter approach, which allows to obtain its real and imaginary parts as the first and second-order terms of the Taylor expansion of the mass operator, computed in the Brueckner-Hartree-Fock method, using the reaction G-matrix built up with the Gogny force instead of the microscopic interaction. This relatively simple approach allows to obtain the optical potential without any additional paramter and, therefore, to explore the ability of this force to describe the phenomenology of the elastic nucleon-nucleus scattering along the periodic table. Our calculation shows that the differential cross sections and analyzing powers describe, qualitatively, the experimental data. However, a more accurate description, similar to that found using global optical model parametrizations fitted to the data [8], requires a renormalization of both, real and imaginary, parts of the optical model computed with our approximation using Gogny forces. It is also interesting to point out that our optical potential without any renormalization is also able to reproduce, at least at qualitative level, elastic cross-section of composite particles by nuclei and quasi-elatic charge exchange reactions A(p,n)B.