Top-antitop production from $W_L^+ W_L^-$ and $Z_L Z_L$ scattering under a strongly-interacting symmetry-breaking sector

TL;DR

This paper develops a theoretical framework using a non-linear electroweak chiral Lagrangian to compute one-loop amplitudes for top-antitop production from vector boson scattering, ensuring unitarity and describing potential resonances.

Contribution

It introduces a new unitarization method supporting resonance poles, enabling a consistent phenomenological description of resonant top-antitop production in strongly interacting EWSB sectors.

Findings

Computed one-loop amplitudes for $W^+W^-$, $ZZ$, and $hh$ to $t\bar t$

Developed a unitarization method with correct analytical properties

Provided a phenomenological model for resonant $t\bar t$ production

Abstract

By using a Non-linear Electroweak Chiral Lagrangian, including the Higgs, coupled to heavy quarks, and the Equivalence Theorem, we compute (in the regime $M_t^2/v^2\ll\sqrt{s}M_t/v^2\ll s/v^2$) the one-loop amplitudes $W^+W^-\to t\bar t$, $ZZ\to t\bar t$ and $hh\to t\bar t$ (to NLO in the effective theory). We calculate the scalar partial-wave helicity amplitudes which allow us to check unitarity at the perturbative level in both $M_t/v$ and $s/v$. As with growing energy perturbative unitarity deteriorates, we also introduce a new unitarization method with the right analytical behavior on the complex $s$-plane and that can support poles on the second Riemann sheet to describe resonances in terms of the Lagrangian couplings. Thus we have achieved a consistent phenomenological description of any resonant $t\bar t$ production that may be enhanced by a possible strongly interacting Electroweak Symmetry Breaking Sector.