The Effective Chiral Lagrangian for a Light Dynamical "Higgs Particle"

TL;DR

This paper extends the effective field theory framework for a light Higgs-like particle, providing a comprehensive basis of operators to connect different electroweak symmetry breaking models and guide experimental searches.

Contribution

It generalizes the CP-even chiral effective operators to include a light Higgs, completing tools to compare linear and non-linear electroweak symmetry breaking realizations.

Findings

Provides a basis for gauge and gauge-Higgs operators up to dimension five.

Facilitates model-independent exploration of exotic gauge-Higgs couplings.

Simplifies fermionic operator analysis using equations of motion.

Abstract

We generalize the basis of CP-even chiral effective operators describing a dynamical Higgs sector, to the case in which the Higgs-like particle is light. Gauge and gauge-Higgs operators are considered up to mass dimension five. This analysis completes the tool needed to explore at leading order the connection between linear realizations of the electroweak symmetry breaking mechanism - whose extreme case is the Standard Model - and non-linear realizations with a light Higgs-like particle present. It may also provide a model-independent guideline to explore which exotic gauge-Higgs couplings may be expected, and their relative strength to Higgsless observable amplitudes. With respect to fermions, the analysis is reduced by nature to the consideration of those flavour-conserving operators that can be written in terms of pure-gauge or gauge-Higgs ones via the equations of motion, but for the standard Yukawa-type couplings.