An Effective Guide to Beyond the Standard Model Physics

TL;DR

The paper develops a coupling-basis construction for dimension-six effective operators in the Higgs/EW sector, arranging the Lagrangian so every operator corresponds to a well-measured coupling and every coupling corresponds to a unique operator direction. By splitting into a starting basis and a disentangled coupling basis, the authors provide explicit CP-even and CP-odd directions across Higgs-only, Higgs–EWPT–TGC, and TGC sectors, with closed-form mappings to the operator content under unitary-gauge reductions. This framework clarifies how experimental constraints translate into constraints on specific Lagrangian directions, exposes correlations among observables, and avoids blind directions, thereby guiding BSM searches in a transparent, testable way. The approach is compatible with existing EFT analyses and reinforces the value of a top-down, direction-based organization of the $d=6$ operator space for electroweak precision and Higgs phenomenology.

Abstract

Effective Lagrangians with dimension-six operators are widely used to analyse Higgs and other electroweak data. We show how to build a basis of operators such that each operator corresponds to a coupling which is well measured or will be in the future. We choose a set of couplings such that the correspondence is one-to-one. In our framework, some important features of the Lagrangian are transparent. For example, one can clearly see the presence or absence of correlations among measurable quantities. This may be a useful guide when searching for physics beyond the Standard Model.