EFT Diagrammatica: UV Roots of the CP-conserving SMEFT

TL;DR

This paper introduces a novel diagrammatic method to identify the UV origins of SMEFT operators, bridging bottom-up and top-down approaches for better understanding of new physics models.

Contribution

It proposes a first-of-its-kind diagrammatic approach to determine heavy field representations associated with SMEFT operators, enhancing model-building and interpretability.

Findings

Established selection criteria for heavy fields based on diagrams

Connected SMEFT operators to specific UV heavy fields

Highlighted the role of non-minimal interactions for certain operators

Abstract

Effective Field Theories are an established framework to bridge the gap between UV and low energy theories. In the context of the Standard Model, the bottom-up approach extends its operator set and thus equips us to astutely probe its observables while encapsulating indirect evidence of unknown high scale theories. While the top-down approach, on the other hand, employs functional techniques to integrate out the heavy fields from a BSM Lagrangian leading to a set of SMEFT operators. An intricate interplay of the two approaches enhances the efficacy of the SMEFT in making meaningful predictions while providing a platform for conducting a coherent comparison of new physics scenarios. However, while the bottom-up approach fails to indicate the origin of the effective operators, the top-down approach is highly dependent on the specific model assumptions of the UV theory. 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. This, in turn, paves the way to construct observable driven new physics models. While we take a predominantly minimalistic approach, we also highlight the necessity for non-minimal interactions for certain operators.