Energy Collider Higgs Physics

The naissance of the gauge theory is an extremely conspicuous step toward the unification of all kinds of interactions. The Standard Model was born in this background and has obtained enormous success. The present precise experimental data have shown an excellent agreement with the predictions of the Standard Model, which based on the SU(3)(?)SU(2)(?)U(1) gauge theory. But another foundation stone of the SM, the Higgs Mechanism, hasn't been proved yet. Therefore people believe that the SM has only been considered to be an effective theory of some underlying theory in low energy.The Minimal Supersymmetry Standard Model (MSSM) and the Large Extra Dimension (LED) Model have solved the hierarchy problem in different ways, and are widely considered as the most appealing extensions of the Standard Model. The MSSM settles the hierarchy problem by introducing supersymmetry and super particles. The Minimal Supergravity (mSUGRA) unification not only provides a framework for the spontaneous breaking supersymmetry, but also can reduce the prediction arbitrariness introduced by the enormous soft breaking terms. The theoretical upper bound on the lightest h~0 mass is 150 GeV after considering two loop radiative corrections. So the lightest h~0 boson cannot escape detection at LCs and in large areas of the parameter space more than one Higgs boson can be found at the LCs.The hierarchy problem can be overcome by adding new dimensions in Large Extra Dimension Model. It's a common thought that the space-time dimensions are larger than 4 in String theory, so the LED can be considered as an effective theory of the String theory. The gravity is involved in this theory, and as Arkani-Hamed, Dimopoulos, and Dvali proposed, the picture of a massless graviton propagating in D dimensions is equivalent with the picture of massive Kaluza-Klein gravitons propagating in 4 dimensions. This makes it possible to study the interaction between the graviton and common SM particles, especially the interaction with Higgs bosons.To search for Higgs bosnon and explore the electroweak symmetry break mechanism is one of the most important missions of future high energy experiments.