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 $\gamma \gamma$, 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 ($500\mathrm{GeV}-3\mathrm{TeV}$). 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.

Comments: 23 pages, 9 figures