We present a simple and consistent way to compute correlation functions in interacting theories with nontrivial phase diagram. As an example we show how to consistently compute the four-point function in three dimensional Z2-scalar theories. The idea is to perform the path integral by weighting the momentum modes that contribute to it according to their renormalization group (RG) relevance, i.e. we weight each mode according to the value of the running couplings at that scale. In this way, we are able to encode in a loop computation the information regarding the RG trajectory along which we are integrating. We show that depending on the initial condition, or initial point in the phase diagram, we obtain different behaviors of the four-point function at the endpoint of the flow.

Physical Review D
Ottawa-Carleton Institute for Physics

Codello, A. (Alessandro), & Tonero, A. (2016). Renormalization group improved computation of correlation functions in theories with nontrivial phase diagram. Physical Review D, 94(2). doi:10.1103/PhysRevD.94.025015