Abstract
The available data on the 125 GeV scalar h is analysed to explore the room for new physics in the electroweak symmetry breaking sector. The first part of the study is model-independent, with h couplings to standard model particles scaled by quantities that are taken to be free parameters. At the same time, the additional loop contributions to h → γγ and h → Zγ, mediated by charged scalar contributions in the extended scalar sector, are treated in terms of gauge-invariant effective operators. Having justified this approach for cases where the concerned scalar masses are a little above the Z-boson mass, we fit the existing data to obtain marginalized 1σ and 2σ regions in the space of the coefficients of such effective operators, where the limit on the h → Zγ branching ratio is used as a constraint. The correlation between, say, the gluon fusion and vector-boson fusion channels, as reflected in a non-diagonal covariance matrix, is taken into account. After thus obtaining model-independent fits, the allowed values of the coefficients are translated into permissible regions of the parameter spaces of several specific models. In this spirit we constrain four different types of two Higgs doublet models, and also models with one or two Y = 2 scalar triplets, taking into account the correlatedness of the scale factors in h-interactions and the various couplings of charged Higgs states in each extended scenario.
Highlights
Various μf, enables one to analyze allowed strengths of effective operators generated in various models
The parts of the contributions from the effective operators OBB and OW W are given in table. 1 while similar contributions from OB and OW are given in table. 2.3 We show in figure 1, the Feynman diagrams contributing to the decays h → γγ and h → Zγ, including those with scaled contribution of SM and those expressed in terms of loop induced dimension-6 operators
After parametrizing new physics effects in the manner discussed above, we investigate the region of parameter space favored by the 8 and 13 TeV results at the LHC
Summary
Where ghV V , ghtt, ghbb and ghττare the couplings of the Higgs to the gauge bosons and the fermions in the SM. Gauge invariance of the Wilson coefficients, will, require that the masses of particles running in the loops should arise from SU(2)L× U(1)Y invariant terms. This requirement is satisfied in each model, involving extension of the electroweak symmetry breaking sector, used by us for illustration. Dimension-6 effective interactions involving a Higgs and two gauge bosons can be expressed in terms of the following gauge-invariant operators [18, 19]: Where. These constitute the most general set of dimension-6 effective operators which give rise to the hγγ and hZγ vertices. Namely that of the signal strengths in the γγ and Zγ channels, has been adopted as a component of the present analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
