On triviality of $\lambda\phi^4$ quantum field theory in four dimensions
Interacting quantum scalar field theories in $dS_D\times M_d$ spacetime can be reduced to Euclidean field theories in $M_d$ space in the vicinity of $I_+$ infinity of $dS_D$ spacetime. Using this non-perturbative mapping, we analyze the critical behavior of Euclidean $\lambda\phi_4^4$ theory in the symmetric phase and find the asymptotic behavior $\beta(\lambda)\sim \lambda$ of the beta function at strong coupling. Scaling violating contributions to the beta function are also estimated in this regime.