Bottoms Up: Standard Model Effective Field Theory from a Model Perspective

💡 Research Summary

The paper “Bottoms Up: Standard Model Effective Field Theory from a Model Perspective” examines the rise of model‑independent strategies in high‑energy physics, focusing on the Standard Model Effective Field Theory (SM‑EFT) as a bottom‑up approach to searching for physics beyond the Standard Model (BSM). After a decade of LHC operations, no clear signals of concrete BSM models (such as supersymmetry, composite Higgs, extra dimensions) have emerged. Consequently, the community’s research agenda has shifted from model‑driven searches toward frameworks that impose only the minimal theoretical constraints required by quantum field theory and the known symmetries of the SM.

The authors first document this shift empirically by mining the arXiv pre‑print archive. Keyword searches for Higgs‑sector papers reveal a steady decline in publications on explicit BSM models (especially SUSY) and a simultaneous rise in the proportion of papers employing Higgs EFT methods—from 3.6 % in 2010 to over 23 % in 2019. This quantitative trend, corroborated by expert interviews, signals a genuine methodological transition within the particle‑physics community.

Three principal strategies for BSM exploration are then outlined: (1) Full BSM models, which introduce new fields and symmetries in a top‑down fashion; (2) Simplified models, which retain only a subset of new particles or interactions from a full model to produce clean experimental signatures; and (3) SM‑EFT, a bottom‑up effective field theory that parametrises possible deviations from the SM by adding higher‑dimensional operators (typically dimension‑6) to the SM Lagrangian. The SM‑EFT Lagrangian reads
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