Introducing tools to test Higgs boson interactions via <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>W</mml:mi><mml:mi>W</mml:mi></mml:math> scattering. II. The coupled-channel formalism and scalar resonances

In this work we explore in detail the presence of scalar resonances $WW$ fusion process context LHC experiments working theoretical framework provided by Higgs Effective Field Theories (HEFT). While phenomenology vector is reasonably understood Weinberg sum-rules and unitarization studies, are a lot less constrained and, more importantly do depend on HEFT low-energy effective couplings different from ones resoances that difficult to constrain experimentally. More specifically, techniques combined with requirement causality allows us set non-trivial bounds self-interactions. This due need considering coupled channels case along process. As byproduct, can gain some relevant information sector $WW\to WW$ elastic processes without needing consider two production.