Dynamics of nou-Iinear Sigma models and their application to the little Higgs models

人们普遍认为，某些“超越标准模态的物理学”应该存在于TeV尺度之上。这些超标准模型（BSM）包括各种Technicolor模型和超对称模型，其中QCD-lice Technicolor模型已被LET和Tevatron上W和Z玻色子的精确测量几乎完全排除。近年来，人们提出了新的ESM模型，如轻盈的Higgs模型和解构的Higgsless模型。这些模型是基于非线性sigma模型的，因此是不可重正化的。因此，分析这些模型（包括其辐射修正）相当困难。在这项研究中，我们从手征微扰论的角度出发，对这些BSM非线性sigma模型进行了全面的分析。对于无希格斯模型，我们发现：1）在任何么正理论中，具有局域费米子的无希格斯模型都不受精确电弱数据的青睐，2）一旦我们允许费米子离域，就有可能构造唯象可行的无希格斯模型，3）假设理想费米子离域的电弱精确参数的偏差最小，（4）这些“理想费米子离域”的无Higgsless模型目前的约束来自于三重规范玻色子顶点的测量我们还对这些模型的手征微扰分析进行了系统的次阶估计，包括辐射修正。

It is widely believed that certain "physics beyond the standard modal" should exist above the TeV scale. These beyond the-standard models(BSM)include various Technicolor models and supeisymmetric model Among them, QCD-lice Technicolor models have been ruled out almost completely by precision measurements of W and Z bosons at LET and Tevatron. Also, we have never observed SUSY partner particles as predicted in SUSY models.Recently, new type of ESM, such as the lithe Higgs models and the deconstructed Higgsless models, has been proposed. There models ale based on the non-linear sigma models, and are thus non-renormalizable. It is therefore quite difficult to analyze these modals including their radiative corrections.In this study, from a viewpoint of chiral perturbation theory, we performed a comprehensive analysis on these BSM non-linear sigma models For Higgsless models, we lurid that 1) in any unitary theory, Higgsless models with localized fermion am disfavored by precision electroweak data, 2) it is possible to construct phenomenologically viable Higgsless models once we allow the fermion delocalization, 3) assuming ideal fermion delocalization" deviations in electroweak precision parameters axe minimized, 4) the current constraint on these “ideal fermion delocalization" Higgsless models comes from the measurement of the triple gauge boson vertices We also perfumed a systematic next order evaluation in the chiral perturbation analysis including the radiative corrections in these models.