The Study Of The Pp�'∏_t~+∏_t~-, ∏_t~0∏_t~0, H_t~0∏_t~0 Processes At The LHC In The TC2 Model

As a low-energy effective theory , the Standard Model (SM) is a pillar of success . It was also proved to be the most successful and the maturest theory of particle physics and has been tested by a lot of experiments, especially for the experimental datas of high energy collidersin the past thirty years. Nonetheless, the standard model still has a series of problems.The dynamics underlying the electroweak symmetry breaking mechanism is still unknown,so it can not explain the dynamics which reponses for the generation of masses; In addition, the introducing of higgs field has made this theory suffers from the problems of triviality and unnaturalness. So people guessed that there might be new physics existence beyond the SM, If no new physics, these problems could not get comparative simple self-consistent explanation. So physical society spend a lot of time and effords to undertake this aspect meaningful explorations, and also brought forward many new physics theory (for example: the dynamic of electroweak symmetry breaking model, supersymmetry model and so on), they expect to solve the problem of the standard model. At the same time, people also did a lot of phenomenological work in these new proposed physics model , to offer valid theoretical guidance for the examination of these models.Among these new physics theories, there is an important and prospective one, so-called technicolor theories. It is a dynamical EWSB theories and havs been well developed in the past three decades. In the 1990s, a new strong dynamic called topcolor was introduced into the technicolor (TC) theories, and the new theory called topcolor assisted technicolor(TC2) model. The TC2 model brought us not only the reasonable dynamical mechanism for the EWSB, but also the solution to the large mass problem of the top quark. So the TC2 model becomes a relatively good and popular model, Our work are based on this model.The TC2 model has predicted some new particles, and the most basic prediction is the existence of the three Pseudo-Goldstone bosons called top-pions(Π_t~±,Πt0) and one scalar boson called top-higgs( ht 0) in a few hundred GeV region. Since the top-pions and top-higgs are regarded as the typical particles of the TC2 model, it could be a good approach to examine the TC2 model by detecting these particles at the high energy colliders.In this paper, We firstly reviewed the basic ideas and the development of TC theory, then we introduced our work: the study of∏_t~+∏_t~-,Π_t~0Π_t~0,ht 0Π_t~0 pair production at the LHC in the TC2 model. The results show that in the parameter space we selected , the production cross section of the∏_t~+∏_t~- process can reach 30 pb, the production cross section of theΠ_t~0Π_t~0 process can reach 340 fb, the production cross section of theΠ_t~0 h_t~0 process can reach 250 fb. considering the yearly luminosity of the LHC can be 100 fb-1, there must be considerable signals produced via these processes, that will provide us a unique chance to do directly searches for the featured particles of TC2 model. It is also found that the light top-pions and top-higgs are favorable by the LHC experiments through the influences of the three free parameters (ε,m∏t),light TC2 featured particles is bigger, which means more production events, furthermore the light TC2 featured particles have more clean signals. In a word, it can provide us very valuable information for testing the TC2 model by investigating the pp�'∏_t~+∏_t~-,Π_t~0Π_t~0,h_t~0Π_t~0processes at the LHC. A short summary has benn given in the last chapter.