Superfluid State in Neutron Star Matter. II

Abstract

By applying the formulation developed in I and using several semiphenomenological two-nucleon potentials, properties of the 3P2 pairing originating from spin-orbit forces are investigated at high density ({rho}{gtrsim}2x1014 gcm-3) in neutron star matter. All the possible types of solutions are obtained by solving a coupled integral gap equation through an iterative procedure. Two of these five solutions represent axially symmetric energy gap. By a kind of self-consistency implied in the coupled gap equation the most general solution shows remarkable deviation from axial symmetry as a result of the mixing mainly of mj={+/-}2, 0 components but the resulting gap is nodeless. The total energy shifts are very close for all the types of solutions. Although calculations show the largest energy shift for the most general solution, this conclusion is a delicate quantitative one. The 3P2 gap at high densities depends critically on the effective mass and short-range behaior of nuclear forces, especially on the strong repulsive core of two-nucleon forces. In any case there exists neutron superfluidity due to the 3P2 pairing at least in the density region {rho}\cong(2[~]5)x1014 gmc-3. Consequences of the calculated results are discussed, and an agreement is given to the connection between the mass of the pulsar and the strong density dependence of neutron superfluidity.