Sommaire:

So far LHC has found only a relatively light Higgs boson with mass mh=126 GeV and no beyond-SM particle has appeared yet below the TeV. Likewise, there have been no significant deviations in the interaction couplings with respect to the expected SM values. EW chiral Lagrangians are found to be, therefore, a natural and systematic approach for the study of this type of scenarios. However, due to the tight constraints from LHC data, one needs to go beyond the leading order approximation in order to disentangle possible new physics. This is, full one-loop effects must be computed and handled in a systematic way; tree-level phenomenological estimates are simply not accurate enough and miss crucial contributions. More specifically, I will discuss the one-loop calculation of the oblique S and T parameters within strongly-coupled models. First we will extract their expressions at next-to-leading order in a generic low-energy theory. In a second step, we will look at the particular predictions that arise in strongly-coupled models with resonances. On the contrary to a widely spread believe, we demonstrate that strongly coupled EW models with massive resonances are not in conflict with the experimental S and T and the recently discovered Higgs-like particle as far as the masses of the new vector and axial-vector resonance lie above the TeV scale and the hWW coupling remains close to the Standard Model one. All through the talk we will employ usual QCD tools such as effective chiral Lagrangians and dispersion relations.

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