Resonances in W_L W_L, Z_L Z_L and hh scattering from dispersive analysis of the non-linear Electroweak+Higgs Effective Theory

TL;DR

This paper discusses a model-independent approach using Unitarized Effective Theory to analyze potential new resonances in electroweak symmetry breaking sector, focusing on scattering of longitudinal gauge bosons and Higgs bosons in the 1-3 TeV range.

Contribution

It introduces a dispersive analysis framework for electroweak and Higgs boson scattering, incorporating unitarization techniques to identify possible resonances in a largely model-independent way.

Findings

Identification of parameter space for 2-TeV resonances.

Potential for simultaneous scalar and vector resonances.

Highlighting the role of coupled-channel dynamics.

Abstract

If new resonances of the electroweak symmetry breaking sector (longitudinal-gauge and Higgs) bosons are found in the 1-3 TeV region, the right tool to assess their properties and confront experimental data in a largely model-independent yet simple manner is Unitarized Effective Theory. Its ingredients are: 1) custodial symmetry and the Equivalence Theorem, that allow to approximate W_L and Z_L by an isospin-triplet of Goldstone bosons omega^a in the 1-TeV region. 2) The effective coupling of a generic, approximately massless scalar-isoscalar h to those Goldstone bosons, and the chiral Lagrangian describing them, valid up to about 3 TeV. 3) The Inverse Amplitude or other unitarization techniques that allow to extend the reach of perturbation theory to the first resonance in each partial wave. We highlight some of the parameter space that can give rise to 2-TeV resonances, for example a simultaneous scalar-isoscalar and a vector-isovector ones (motivated by the ATLAS excess) and also the potential importance of coupled-channel dynamics between hh and omega omega.