consider single band
1, only for centrosymmetric sc, we have definite odd-parity or even parity, is this right? how about non-centrosymmetric sc?
2, for centrosymmetric sc, in normal state we have inversion symmetry, and for sc state, inversion symmetry only holds for even parity, while fails in odd parity, is this right?
3,is spin triplet pair always break time reversal symmetry? why?