Spectral representation in stochastic quantization

A spectral representation of stationary two-point functions is investigated on the basis of the operator formalism in stochastic quantization. Assuming the existence of asymptotic noninteracting fields, we can diagonalize the total Hamiltonian in terms of asymptotic fields and show that the correlation length along the fictitious time is proportional to the physical mass expected in the usual field theory. A relation between renormalization factors in the operator formalism is derived as a by-product and its validity is checked with the perturbative results calculated in this formalism.