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The road to the ElectroWeak Symmetry Breaking Mechanism
Sara Bolognesi (CERN)
Seminar Room 3, 15.00h
The LHC experiments are today focused on the search of an "Higgs-like" resonance. The Standard Model Higgs boson has been excluded by CMS with mass between 127-600 GeV and the focus is now on the low mass region (~120 GeV) just above the LEP limit.
In this hectic moment we should not forget that the main role of the Higgs mechanism in the Standard Model (SM) is related to the ElectroWeak Symmetry Breaking Mechanism (EWSB). As I will shortly remind, the Higgs boson is needed in the SM to guarantee the unitarity of the VV scattering process. Whatever resonance we may see (or not see) at low mass (mH<2*mW), in order to be the SM Higgs it must play the role of restoring the unitarity in VV scattering. Therefore the final understanding of the EWSB may come only from a detailed study of the VV final state.
I will summarize the main challenges which we will face next year in the search for a generic X->VV->4f resonance at high mass and on the road to a precise measurement of the VV scattering spectrum, which will be achievable with larger luminosity (>50-100 fb-1). Until limited luminosity will be available, the semileptonic final state (ll/ln+2j) will be crucial, thus making the control of V+jets background the main issue to face. Increasing luminosity, the understanding of the Electroweak continuum VV production on the theoretical side will become critical.