Equation of state of superfluid neutron matter and the calculation of the 1S0 pairing gap

We present a quantum Monte Carlo study of the zero-temperature equation of state of neutron matter and the computation of the ^1 S_0 pairing gap in the low-density regime with \rho < 0.04 fm^{-3} . The system is described by a non-relativistic nuclear Hamiltonian including both two- and three-nucleon interactions of the Argonne and Urbana type. This model interaction provides very accurate results in the calculation of the binding energy of light nuclei. A suppression of the gap with respect to the pure BCS theory is found, but sensibly weaker than in other works that attempt to include polarization effects in an approximate way.