Scalar fields in the de Sitter spacetime

Abstract We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime. For the theory with a quartic self-interaction, two-point function is calculated up to two loops. Comparing our results Hartree-Fock approximation and stochastic approach shows that former resums only cactus type diagrams, whereas latter contains sunset diagram as well produces correct result. compare preceding obtained for massless field.