Abstract
We present a short overview of the main aspects of the Higgs Effective Lagrangian. In particular we highlight a strategy to determine whether the electroweak symmetry breaking sector is controlled by a strong or a weak dynamics. We give an estimate of the effects of the effective operators on physical observables and review the most important bounds on the Wilson coeffcients of the effective operators.
Highlights
The most general and systematic classification of the dimension-6 operators for a weak doublet H was made in Ref. [4]
In order to investigate the nature of the dynamics behind the EW symmetry breaking, it can be crucially helpful to identify which operators of the Higgs Effective Lagrangian (HEL) can probe the strength of the Higgs couplings to the states belonging to the new dynamics, and which operators are sensitive only to the mass scale M
We start recalling the classification of the dimension6 operators proposed in Ref. [6], that is based on an expansion of the HEL in the number of fields and derivatives: any extra derivative costs a factor 1/M, and any extra Higgs field brings a factor 1/ f ≡ g∗/M, where g∗ ≤ 4π is the generic coupling of the Higgs boson to the New Physics (NP) states
Summary
After the discovery of a boson with mass mh 125 GeV by both the ATLAS [1] and CMS [2] collaborations, it is of crucial importance to find the best strategy to study the properties of the new particle, and to investigate the nature of the mechanism behind the electroweak (EW) symmetry breaking. As the production cross section and decay rates of the new boson are compatible with those of the Standard Model (SM) Higgs boson, and no hint of the existence of additional new resonances has revealed itself yet, a parametrization in terms of effective operators seems to be the most appropriate approach to investigate the properties of the new boson Such an effective description is valid as long as New Physics (NP) states appear at a scale M mh, and is based on an expansion in the number of fields and derivatives [3]. In the light of the current experimental measurements, it is reasonable to assume that the new boson h is a CP-even scalar that forms an S U(2)L doublet together with the longitudinal polarizations of the W and Z, so that at high energies the S U(2)L×U(1)Y EW symmetry is linearly realized Under these assumptions, the Higgs Effective Lagrangian (HEL) is formed by a sum of operators of increasing dimensionality, where the leading NP effects are given by dimension-6 operators. In this proceeding we will summarize the main results pointed out in Ref. [7]
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