One-loop calculation of the oblique S and T parameters within strongly-coupled scenarios with a light Higgs-like boson

TL;DR

This paper calculates the oblique S and T parameters at one-loop level in strongly-coupled models with a light Higgs-like boson, using an effective Lagrangian and dispersive methods, revealing constraints on resonance masses and Higgs couplings.

Contribution

It provides a novel one-loop calculation of electroweak oblique parameters in strongly-coupled scenarios with a light Higgs, incorporating short-distance constraints and resonance effects.

Findings

Resonance masses are constrained to be above the TeV scale.

Higgs-like scalar's WW coupling is close to the Standard Model value.

Experimental data restricts the parameter space of strongly-coupled models.

Abstract

We present a one-loop calculation of the oblique S and T parameters within strongly-coupled models of electroweak symmetry breaking with a light Higgs-like boson. We use a general effective Lagrangian, implementing the chiral symmetry breaking SU(2)_L x SU(2)_R -> SU(2)_{L+R} with Goldstones, gauge bosons, the Higgs-like scalar and one multiplet of vector and axial-vector massive resonance states. The estimation is based on the short-distance constraints and a dispersive approach. The experimentally allowed range forces the vector and axial-vector states to be heavy, with masses above the TeV scale, and suggests that the Higgs-like scalar should have a WW coupling close to the Standard Model one.