Nuclear energy density functional from chiral pion–nucleon dynamics Original Research Article

We calculate the nuclear energy density functional relevant for N=Z even–even nuclei in the framework of chiral perturbation theory. The calculation includes the one-pion exchange Fock diagram and the iterated one-pion exchange Hartree and Fock diagrams. From these few leading order contributions in the small momentum expansion one obtains already a good equation of state of isospin symmetric nuclear matter. We find that in the region below the nuclear matter saturation density the effective nucleon mass View the MathML source deviates by at most 15% from its free space value M, with View the MathML source for View the MathML source and View the MathML source for higher densities. The parameterfree strength of the View the MathML source-term, F∇(kf), is at saturation density comparable to that of phenomenological Skyrme forces. The magnitude of FJ(kf) accompanying the squared spin–orbit density View the MathML source comes out considerably larger. The strength of the nuclear spin–orbit interaction, Fso(kf), as given by iterated one-pion exchange is about half as large as the corresponding empirical value, however, with the wrong negative sign. The novel density dependencies of View the MathML source and F∇,so,J(kf) as predicted by our parameterfree (leading order) calculation should be examined in nuclear structure calculations (introducing at least an additional short range spin–orbit contribution constant in density).