Abstract
Abstract The 8 TeV LHC Higgs search data just released indicates the existence of a scalar resonance with mass ~ 125 GeV. We examine the implications of the data reported by ATLAS, CMS and the Tevatron collaborations on understanding the properties of this scalar by performing joint fits on its couplings to other Standard Model (SM) particles. We discuss and characterize to what degree this resonance has the properties of the SM Higgs, and consider what implications can be extracted for New Physics in a (mostly) model-independent fashion. We find that, if the Higgs couplings to fermions and weak vector bosons are allowed to differ from their standard values, the SM is ~ 2σ from the best fit point to the current data. Fitting to a possible invisible decay branching ratio, we find BRinv ≃ 0.05 ± 0.32 (95% C.L.). We also discuss and develop some ways of using the data in order to bound or rule out models which modify significantly the properties of this scalar resonance, and apply these techniques to the current global dataset.
Highlights
At this time, the existing experimental evidence is not sufficiently strong to directly assume that the scalar resonance is the Standard Model (SM) Higgs boson, ascribing any deviations in the measured properties of the scalar field directly to the effects of NP interactions expressed through higher dimensional operators
In order to establish experimentally the properties of the scalar resonance in a model-independent way, one can utilize the effective field theory of the chiral EW Lagrangian coupled to a scalar field that was emphasized in refs. [3, 14] to study recent Higgs signal-strength data
The main difference between the results presented in figure 3 with respect to the first version of this paper comes from the use of the ATLAS combined signal strength reported in ref. [1], that incorporates the large 8 Tev ATLAS WW [60] signal strength μW W = 2.1+−00
Summary
An effective chiral EW Lagrangian with a nonlinear realization of the SU(2)L × U(1)Y symmetry gives a minimal description of the (non-scalar) degrees of freedom of the SM consistent with the assumptions of SM-like SU(2)c violation and MFV. When one assumes that h is embedded into an SU(2)L doublet - H - as in the SM, the operators in L5HD first appear at dimension six, and the coefficients are suppressed by an extra factor of v/Λ when considering single scalar production. Where Fμ ν is the electromagnetic field strength tensor and cγ = cW + cB in the case of an SU(2)L singlet field, and cγ = cW + cB − cW B if h is embedded into an SU(2)L doublet In this manner, one can understand that the choices to retain the effects of higher dimensional operators (or not) in performing global fits introduces implicit UV dependence. In this case, a, c are free parameters in general, they can be fixed in particular UV completions. The classes of models discussed above can be considered as motivating examples
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