Constraining the neutron-proton effective mass splitting in neutron-rich matter

Within Bombaci's phenomenological single-nucleon potential model we study the neutron-proton effective mass splitting $m_n^*- m_p^*$ in neutron-rich matter. It is shown that an effective mass splitting of $m_n^*<m_p^*$ leads to a symmetry potential that is inconsistent with the energy dependence of the Lane potential constrained by the nucleon-nucleus scattering experimental data.