Coupling WW, ZZ unitarized amplitudes to gamma gamma in the TeV region

Abstract

We define and calculate helicity partial-wave amplitudes for processes linking the Electroweak Symmetry Breaking Sector (EWSBS) to γ γ , employing (to NLO) the Higgs-EFT (HEFT) extension of the Standard Model and the Equivalence Theorem, while neglecting all particle masses. The resulting amplitudes can be useful in the energy regime (500 GeV−3 TeV). We also deal with their unitarization so that resonances of the EWSBS can simultaneously be described in the γ γ initial or final states. Our resulting amplitudes satisfy unitarity, perturbatively in α, but for all s values. In this way we improve on the HEFT that fails as interactions become stronger with growing s and we provide a natural framework for the decay of dynamically generated resonances into W W, Z Z and γ γ pairs.