Oct 2023 - Sep 2024

Three Pillars of EFT

by Shakeel Rahaman




Effective Field Theory is a well-established platform for connecting UV and low energy theories. I will outline three potential applications for it in this talk. The bottom-up approach augments the renormalizable Lagrangian with higher dimensional operators. This empower us to carefully analyse the observables that could encapsulate indirect evidence of high-scale theories we are unable to pin point. On the other hand, the top-down approach integrate out heavy fields from the BSM Lagrangian, which leads to a set of Standard Model Effective Field Theory (SMEFT) operators. An intricate connection between the two approaches makes it easier for the SMEFT to make accurate predictions and gives a opportunity to compare new physics scenarios in a rational manner. But while the bottom-up method doesn't explain where the effective operators come from, the top-down method is very dependent on the UV theory. The third way is using Feynman diagrams to set selection criteria for the heavy field representations that are allowed for each SMEFT operator. This, in turn, makes it possible to build new physics models that are based on information that can be observed.