Little Higgs Models And The Single Top Production At The Hadron Collider

Content: The discovery of the top quark in 1995, by the CDF and DO collaborations at the Fermilab Tevatron, marked the dawn of a new era in particle physics. The top quark, with a mass of the order of the electroweak scale m_t = 172.7±2.9GeV is the heaviest particle yet discovered and might be the first place in which new physics effects could appear. In recent years, the little Higgs theory is one kind of the pooular new physical theories. The littlest Higgs model and the SU(3) simple group model provide an economical approach which implements the ideas of the little Higgs theory. In this paper, we investigate the corrections of the littlest Higgs model and the SU(3) simple group model to single top production and whether it can be detected at the LHC experiments.In the first two part, we present an overview of Top Quark Physics-from what has been learned so far at the Tevatron, to the searches that lie ahead at present and future colliders. Top quark physics inclode top quark propertities, top quark production, top quark decay and top detecting. We summarize the richness of the measurements and discuss their possible impact on our understanding of the Standard Model by pointing ont their key elements and limitations. When possible, we discuss how the top quark may provide a connection to new or unexpected physics. In the third part, we introduce the Little Higgs model. We categorize the many little Higgs models into two class: product group model and simple group model, which based on the structure of the extended electroweak gauge group. As representatives of the two classes, we study the Littlest Higgs(LH) model and the SU(3) simple group model. Little Higgs models predict new gauge bosons, fermions and scalars at the TeV scale that stabilize the Higgs mass against quadratically divergent one-loop radiative corrections. We find that by steadying the couplings of the new gauge bosons to the light Higgs boson and to the Standard Model fermions, one can confirm the little Higgs mechanism and determine the structure of the extended electroweak gauge group.In last part, we investigate the corrections of the littlest Higgs model and the SU(3) simple group model to single top production at the CERN Large Hardron Collider(LHC). There are three production processes:s- channel process q + (?)→t + (?), t-channel process q + b→q′+ t or (?) + b→t + (?) and tW associated production process. For f≥1TeV , 0.4≤x_L≤0.6 , 0＜c≤0.5[63] in the LH model, the absolute values of the relative correction△σ_i/σ_i^SM are smaller than 2% ; For f≥1TeV, x_λ＞1 , t_β＞1[64] in the SU(3) simple group model, the absolute values of the relative correction for t-channel, s-channel, and tW associated production processes are in the ranges of 4.3%～10.8%, 3.1%～7.5%, and2%～10.6%, respectively. We find that the new gauge bosons W_H^±, X^- predicted by the LH model can generate significant contributions to single top production via the s-channel process. We expect that the effects of the LH model and the SU(3) simple group model on singel top prodnction can be detected at the LHC experiments.