Low-momentum relativistic nucleon-nucleon potentials: Nuclear matter

A series of relativistic one -boson -exchange potentials for a two -nucleon system, denoted as OBEPA, is constructed with a momentum cutoff A ranging from infinity to 2 fm-1. These potentials are developed by simultaneous fitting to nucleon -nucleon (NN) scattering phase shifts, low -energy scattering length, effective range, and the binding energy of the deuteron. The momentum -space matrix elements of the low -momentum OBEPA (A 3 fm-1) demonstrate consistency with the universal behaviors observed in other realistic NN potentials evolved by renormalization group methods. These OBEPAs are applied to calculate the equation of state of symmetric nuclear matter (SNM) within either the nonrelativistic (NR) Brueckner-Hartree-Fock (BHF) or relativistic Brueckner-Hartree-Fock (RBHF) frameworks. The results show that the saturation properties of SNM are reproduced qualitatively from the RBHF calculation, but not from the NR-BHF calculation. This study highlights the relativistic mechanism in explaining the saturation properties of nuclear matter. The remaining discrepancy in reproducing empirical saturation properties in the RBHF calculation using the OBEPAs signals the necessity of including three -nucleon correlations or genuine three -nucleon forces.