Nucleon effective E-mass in neutron-rich matter from the Migdal–Luttinger jump

The well-known Migdal–Luttinger theorem states that the jump of the single-nucleon momentum distribution at the Fermi surface is equal to the inverse of the nucleon effective E-mass. Recent experiments studying short-range correlations (SRC) in nuclei using electron–nucleus scatterings at the Jefferson National Laboratory (JLAB) together with model calculations constrained significantly the Migdal–Luttinger jump at saturation density of nuclear matter. We show that the corresponding nucleon effective E-mass is consequently constrained to M0⁎,E/M≈2.22±0.35 in symmetric nuclear matter (SNM) and the E-mass of neutrons is smaller than that of protons in neutron-rich matter. Moreover, the average depletion of the nucleon Fermi sea increases (decreases) approximately linearly with the isospin asymmetry δ   according to κp/n≈0.21±0.06±(0.19±0.08)δκp/n≈0.21±0.06±(0.19±0.08)δ for protons (neutrons). These results will help improve our knowledge about the space–time non-locality of the single-nucleon potential in neutron-rich nucleonic matter useful in both nuclear physics and astrophysics.