Isospin splitting of the nucleon mean field

The isospin splitting of the nucleon mean field is derived from the Brueckner theory extended to asymmetric nuclear matter. The Argonne ${V}_{18}$ has been adopted as bare interaction in combination with a microscopic three-body force. The isospin splitting of the effective mass is determined from the Brueckner-Hartree-Fock self-energy: It is linear according to the Lane ansatz, such that ${m}_{n}^{*}>{m}_{p}^{*}$ for neutron-rich matter. The symmetry potential is also determined, and a comparison is made with the predictions of the Dirac-Brueckner approach and the phenomenological interactions. The theoretical predictions are also compared with the empirical parametrizations of neutron and proton optical model potentials based on the experimental nucleon-nucleus scattering and the phenomenological ones adopted in transport model simulations of heavy-ion collisions. The direct contribution of the rearrangement term due to three-body forces to the single-particle potential and symmetry potential is discussed.

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