Local contractivity of the $\Phi_0^4$ mapping
  Previous results about the non trivial solution of the $\Phi^4$-equations of motion for the Green's functions in the Euclidean\ space (of $0\leq r\leq 4$ dimensions) in the Wightman Quantum Field theory framework, are reviewed in the 0 - dimensional case from the following three aspects: The structure of the subset $\Phi \subset {\cal B}$ characterized by the signs and "splitting" (factorization properties) is reffined and more explictly described by a subset $\Phi_0\subset \Phi$   The local contractivity of the corresponding $\Phi ^4_0$ mappping is established in a neighborhood of a precise nontrivial sequence $H_0\in \Phi_0$ using a new norm in the Banach space $ {\cal B}$. A new $\Phi ^4_0$ iteration is defined in the neighborhood of this sequence $H_0\in \Phi_0 $ and our numerical study displays clearly the stability of $\Phi_0$ (the splitting, the bounds and sign properties are perfectly illustrated), and a rapid convergence to the unique fixed point $H^* \in \Phi_0$. 
Marietta Manolessou
math-ph math.MP