Constraints on the possible pairing symmetry of iron arsenide superconductors in a two-orbital model

In this work, we establish a few exact identities through commutation of intraorbital and interorbital on-site pairings with a two-orbital model describing the FeAs-based superconductors. Applying the conclusion drawn from rigorous relation and physical interpretation, we give constraints on the possible symmetries of the superconducting pairing of the model. Hence the favorable pairings in high-temperature oxypnictide superconductors are proposed.