Equation of state of low-density neutron matter, and the 1S0 pairing gap

We report results of the equation of state of neutron matter in the low-density regime, where the Fermi wave vector ranges from 0.4≤kF≤1.0 fm-1. Neutron matter in this regime is superfluid because of the strong and attractive interaction in the 1S0 channel. The properties of this superfluid matter are calculated starting from a realistic Hamiltonian that contains modern two- and three-body interactions. The ground state energy and the 1S0 superfluid energy gap are calculated using the auxiliary field diffusion Monte Carlo method. We study the structure of the ground state by looking at pair distribution functions as well as the Cooper-pair wave function used in the calculations.