  We define and calculate helicity partial-wave amplitudes for processes
linking the Electroweak Symmetry Breaking Sector (EWSBS) to $\gamma\gamma$,
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 ($500\,{\rm GeV}-3\,{\rm TeV}$).
We also deal with their unitarization so that resonances of the EWSBS can
simultaneously be described in the $\gamma\gamma$ initial or final states. Our
resulting amplitudes satisfy unitarity, perturbatively in $\alpha$, but for all
$s$ values. In this way we improve on the HEFT that fails as interactions
become stronger with growing $s$ and provide a natural framework for the decay
of dynamically generated resonances into $WW$, $ZZ$ and $\gamma\gamma$ pairs.
