Superfluid State in Neutron Star Matter. I

Superfluid state originating from the 3P2 pairing is investigated for the high density part of neutron state (ρ≳1/2 ρ(nuclear matter) = 1.6 ×1014 gcm-3), where the pairing interaction is most attractive in the 3P2 state due to spin-orbit forces. In order to treat such a nonzero angular momentum pairing, generalization of the Bogoliubov transformation is developed. Applications of this formalism to several cases are given. For the 3P2 pairing in neutron star matter, calculations are made for a special but characteristic coupling leading to an anisotropic energy gap. The results by use of a nonlocal separable potential show that there certainly exists the 3P2 gap with 1 ∼3 MeV for the density ρ≳2 ×1014 gcm-3 (EF ≳50 MeV).