The Chiral Approach to the Electroweak Interactions

TL;DR

The work presents a chiral, non-linear effective field theory framework for electroweak interactions, outlining how spontaneous symmetry breaking can be encoded without a light Higgs and how higher-dimension operators organize quantum corrections. The key approach is to relate low-energy observables to a small set of oblique parameters $\epsilon_1,\epsilon_2,\epsilon_3$ (and their EFT counterparts $a_i$) through precise gauge-boson self-energies and to use matching conditions to connect heavy new physics to the effective Lagrangian. The analysis shows how LEP I/II data constrain the EFT coefficients and how heavy states can yield non-decoupling effects, with explicit mappings from fundamental theories to the operator basis. The framework provides a model-independent tool to interpret precision EW measurements and to anticipate how future collider data could reveal or constrain physics beyond the Standard Model.

Abstract

The effective lagrangian approach is reviewed and applied to the case of electroweak interactions.