Electroweak resonances in HEFT

TL;DR

This paper develops a unitarized effective field theory framework to describe potential electroweak resonances in the 0.5-3 TeV range, applicable to various beyond Standard Model scenarios, and assesses its systematic reliability.

Contribution

It introduces a unitarized HEFT approach for modeling electroweak resonances and compares multiple methods to ensure robustness in the nonperturbative regime.

Findings

Methods produce qualitatively similar unitarized amplitudes.

Framework valid for 0.5-3 TeV resonance region.

Couplings to top-antitop and photon channels computed.

Abstract

Due to the gap between the known 100 GeV scale and new physics if any, it is natural to employ an effective one-loop Lagrangian (HEFT) for the particles of the Electroweak Symmetry Breaking Sector (W_L, Z_L and h). To describe any new particles and resonances that may be found at the LHC we employ its unitarized amplitudes, valid even in the presence of new strong interactions. We have assessed the systematics by comparing several such methods, and find that they give qualitatively similar results and succesfully produce unitary amplitudes in the nonperturbative regime. We are thus in a position to describe new physics in the 0.5 TeV-3 TeV (region of validity of our approximations: the effective theory and the equivalence theorem to substitute W_L, Z_L by the Goldstone bosons of electroweak symmetry breaking). We have also computed the coupling of the EWSBS to the top-antitop and two-photon channels to describe resonances that decay through them or to study their photon-photon production, for example. The approach is universal and useful for many BSM theories at low energy.