EFT diagrammatica: UV roots of the CP-conserving SMEFT

Abstract

The Standard Model Effective Field Theory (SMEFT) is an established theoretical framework that parametrises the impact a UV theory has on low-energy observables. Such parametrization is achieved by studying the interactions of SM fields encapsulated within higher mass dimensional (≥ 5) operators. Through judicious employment of the tools of EFTs, SMEFT has become a source of new predictions as well as a platform for conducting a coherent comparison of new physics (beyond Standard Model) scenarios. We, for the first time, are proposing a diagrammatic approach to establish selection criteria for the allowed heavy field representations corresponding to each SMEFT operator. We have elucidated the links of a chain connecting specific CP conserving dimension-6 SMEFT operators with unique sets of heavy field representations. The contact interactions representing each effective operator have been unfolded into tree- and (or) one-loop-level diagrams to reveal unique embeddings of heavy fields within them. For each case, the renormalizable vertices of a UV model serve as the building blocks for all possible unfolded diagrams. Based on this, we have laid the groundwork to construct observable-driven new physics models. This in turn also prevents us from making redundant analyses of similar models. While we have taken a predominantly minimalistic approach, we have also highlighted the necessity for non-minimal interactions for certain operators.