Wick’s theorem for nonsymmetric normal ordered products and contractions
Wick’s theorem for nonsymmetric normal ordered products and contractions
We consider arbitrary splits of field operators into two parts; ψ=ψ++ψ−, and use the corresponding definition of normal ordering introduced earlier [T. S. Evans and D. A. Steer, Nucl. Phys. B 474, 481 (1996)]. In this case the normal ordered products and contractions have none of the special symmetry properties …