The photon photon scattering into longitudinal weak gauge bosons ( AA-->ZL ZL and AA-->WL+WL-) can be used to study the Higgs properties and discern possible new physics in present a future collider experiments. The analysis is taken up to NLO, this is, up to the one-loop level, within the non-linear (chiral) EW low-energy theory. In this away we allow for the most generic type of underlying new physics scenarios, both perturbative and strongly-coupled. We take an effective field theory approach where we consider the EW chiral Lagrangian including a light Higgs-like scalar (ECLh) as a dynamical light field together with the would-be-Goldstone bosons associated to the electroweak symmetry breaking. This description assumes the existence of a mass gap between mh, mW, mZ and the potential new emergent resonances, setting an intermediate energy region (above mh, mW, mZ and below the resonance masses) where the use of the ECLh is the most appropriate tool to compute and relate different observables. The chiral counting rules for the present case, the photon-photon scattering, will be reviewed in detail. The distinctive signal we found in our theoretical prediction leads to interesting implications both theoretically and experimentally. After extremely subtle cancellations the final amplitudes happen to be UV finite, being determined by a set of renormalization group invariant combinations of effective couplings. We finally propose a joint analysis of our results for the photon-photon scattering amplitudes together with other photonic processes and electroweak precission observables for a future comparison with data. This combined analysis could help to disantangle the nature of the light Higgs-like particle.Finally, we provide some estimates of possible phenomenological signals in colliders and study the relevance of both loop and tree-level contributions in the photon-photon cross section.

    Host: Prof. Wei Wang