Non-perturbative construction of counterterms for 2PI-approximation

A concise method is presented for the non-perturbative computation of the counterterms renormalising 2PI-actions. The procedure is presented for a real scalar field up to O(λ2) order in the skeleton truncation of Γ2PI with respect to the self-coupling, and in a constant symmetry breaking background. The method is easily generalizable to field theories with arbitrary global symmetry.