Anti-parallel spin pairing in color superconductivity

We investigate helicity states of Cooper pairs in quark matter on the basis of a QCD-like theory. The Cooper pair consists of spin-triplet states with one-flavor quark matter if an s-wave and a color-antisymmetric state are assumed. There are two types of spin pairing schemes, parallel and anti-parallel spin pairing. The gap equations are derived in both cases and solved numerically. It is shown that the energy gap in the anti-parallel spin pairing case is larger than that in the parallel case. This is caused by the color-magnetic interaction. It is concluded that the anti-parallel spin pairing scheme is more stable than the parallel one.