Renormalization of Scalar and Fermion Interacting Field Theory for Arbitrary Loop: Heat-Kernel Approach

Abstract: We outline a proposal, based on the Heat-Kernel method, to compute 1PI effective action up to any loop order for quantum field theory with scalar and fermion fields. We algebraically extract the divergences associated with the composite operators without explicitly performing any momentum loop integral. We perform this analysis explicitly for one and two-loop cases and pave the way for three-loop as well. Using our prescription we compute the two-loop counter terms for a theory containing higher mass dimensional effective operators that are polynomial in fields for two different cases: (i) real singlet scalar, and (ii) complex fermion-scalar interacting theories. We also discuss how the minimal Heat-Kernel fails to deal with the effective operators involving derivatives. We explicitly compute the one-loop counter terms for such a case within an $O(n)$ symmetric scalar theory employing a non-minimal Heat-Kernel. Our method computes the counter terms of the composite operators directly and is also useful for extracting infrared divergence in massless limits.