An asymptotic solution of the system of Schwinger-Dyson equations for
four-dimensional Euclidean scalar field theory with interaction
2λ(ϕ∗ϕ)2 is obtained. For
λ>λcr=16π2 the two-particle amplitude has the
pathology-free asymptotic behavior at large momenta. For λ<λcr
the amplitude possesses Landau-type singularity.Comment: 16 pages; journal version; references adde