3P2superfluidity in neutron star matter

Abstract

${}^{3}{P}_{2}$ superfluidity of neutrons in neutron star matter is investigated using several potential models and the separation method. As a first step, the dependence of the pure ${}^{3}{P}_{2}$ energy gap on the projection $M$ of total momentum $J$ is analyzed. The energy gap functions for pure ${}^{3}{P}_{2}$ pairing are treated as vectors indexed by $M$, and it is shown that the magnitudes of these vectors at Fermi surface are close to each other, whereas their components are different. On the basis of these works, the influence of hyperons on the energy gap for ${}^{3}{P}_{2}$ neutron pairing, with and without coupling to the ${}^{3}{F}_{2}$ state, at Fermi surface in neutron star matter is studied. The results show that in the OPEG case hyperons increase the energy gap when the baryon number density is in the range of 0.2 fm${}^{\ensuremath{-}3}l{n}_{B}l0.33$ fm${}^{\ensuremath{-}3}$ and reduce it when ${n}_{B}g0.33$ fm${}^{\ensuremath{-}3}$, and in the Argonne $\ensuremath{\upsilon}18$ case hyperons increase the energy gap in the whole range where the ${}^{3}{P}_{2}$ superfluidity exists. The energy gaps are zero in two types of neutron star matter for the Bonn potential.