  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.
