Disentangling a dynamical Higgs

Abstract

The pattern of deviations from Standard Model predictions and couplings is different for theories of new physics based on a non-linear realization of the SU(2) L ×U(1) Y gauge symmetry breaking and those assuming a linear realization. We clarify this issue in a model-independent way via its effective Lagrangian formulation in the presence of a light Higgs particle, up to first order in the expansions: dimension-six operators for the linear expansion and four derivatives for the non-linear one. Complete sets of gauge and gaugeHiggs operators are considered, implementing the renormalization procedure and deriving the Feynman rules for the non-linear expansion. We establish the theoretical relation and the differences in physics impact between the two expansions. Promising discriminating signals include the decorrelation in the non-linear case of signals correlated in the linear one: some pure gauge versus gauge-Higgs couplings and also between couplings with the same number of Higgs legs. Furthermore, anomalous signals expected at first order in the non-linear realization may appear only at higher orders of the linear one, and vice versa. We analyze in detail the impact of both type of discriminating signals on LHC physics.

The gauge-Higgs legacy of the LHC Run I

“…This allows us to use Higgs data not only to constrain TGVs [41], but also to use TGV data to test the strengths and structures of Higgs couplings. Usually, such combined analyses rely on LEP results for the TGVs [42][43][44][45][46][47][48][49], the only exception being refs. [22,23].…”

“…The SU(2)-gauge-invariant formulation in terms of dimension-six operators induces correlations of the formerly multi-dimensional space of modified gauge couplings, [44,[51][52][53][54], the parametrization would be extended. In the most generic scenario, the couplings defined in eq.…”

“…Furthermore, the deviations generated by non-linear operators in the TGVs could be completely decorrelated to the deviations generated in the Higgs interactions. As it has been studied in detail in [44,54], this different pattern of anomalous interactions could be potentially used to test the nature of the Higgs boson.…”

Anomalous gauge couplings from composite Higgs and warped extra dimensions

“…7 Because they are typically lighter than other states of the strong sector, their contribution may naturally become the dominant one because of the quadratic and quartic mass dependence. This state may in general have other light companions coming from the embedding in r G .…”

“…The trace of the EM tensor of the massless (elementary) gauge fields vanishes classically but not at the quantum level. The dilaton couples to the large trace anomaly 7 Other light vector-like fermions, such as τ or bottom partners, can be present in some models. Our results trivially generalize to these cases.…”