Superfluidity of neutron matter: (I). Singlet pairing

Abstract

Abstract The possibility of neutron or proton singlet pairing and superfluidity in neutron star matter is investigated, and the energy gap and corresponding critical temperature is calculated or estimated as a function of Fermi momentum or density. The calculations are performed for three different potentials: a “one-pion-exchange gaussian” (OEG) potential, an “effective” OPEG potential, and an effective Reid soft-core potential obtained by a method of “lowest-order constrained variation”. The results indicate that neutron superfluidity, corresponding specifically to 1S 0-state pairing, may exist in a low-density shell in the nuclear-matter region in neutron stars, i.e. for densities 4.6×10 11g/cm 3<ϱ< 1.6 × 10 14g/cm 3, and the maximum self-consistent energy gap is Δ(k n F) ≈ 2–5 MeV for a neutron ermi momentum k n F = 0.7–1.0 fm −1. Superfluidity or superconductivity corresponding to 1S 0-state pairing for the proton subsystem is quite likely at higher densities, i.e. for 2.4 × 10 14g/cm 3 < p < 7.8 × 10 14 g/cm 3, and the maximum energy gap for the OPEG potential is Δ (k p f) ≈ 0.3–0.6 MeV for a proton ermi momentum k p F ≈ 0.7fm −1. The estimated critical t seem to be higher than expected temperatures inside neutron stars.