Isospin dependence of nucleon effective masses in neutron-rich matter

In this talk, we first briefly review the isospin dependence of the total nucleon effective mass M*(J) inferred from analyzing nucleon-nucleus scattering data within an isospin-dependent non-relativistic optical potential model, and the isospin dependence of the nucleon E-mass M*(,E)(J) obtained from applying the Migdal-Luttinger theorem to a phenomenological single-nucleon momentum distribution in nuclei constrained by recent electron-nucleus scattering experiments. Combining information about the isospin dependence of both the nucleon total effective mass and E-mass, we then infer the isospin dependence of nucleon k-mass using the well-known relation M*(J) (=) M*(,E)(J) . M*(,k)(J) Implications of the results on the nucleon mean free path in neutron-rich matter are discussed.