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arXiv 0705.0115hep-ph
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单二重态和顶色辅助人工色模型中电弱手征拉格朗日函数系数的动力学计算

Dynamical Computation on Coefficients of Electroweak Chiral Lagrangian from One-doublet and Topcolor-assisted Technicolor Models

Hong-Hao Zhang, Shao-Zhou Jiang, Qing Wang

摘要:

在前人从QCD第一性原理导出赝标介子手征拉格朗日量的基础上,我们从单偶线人工色模型和顶色辅助人工色模型出发,导出了电弱手征拉格朗日量,并建立了计算其系数的公式。我们发现顶色辅助人工色模型的电弱手征拉氏量系数分为三部分:直接的TC 2相互作用部分,TC 1和TC 2诱导的有效Z'粒子贡献部分,以及普通夸克贡献部分。本文计算了前两个部分,证明了直接相互作用部分与单偶人工色模型中的直接相互作用部分相同,而有效Z'的贡献至少正比于电弱手征拉氏量中的p^2序参量β_1和顶色的典型特征。辅助人工色模型的特点是它只允许正的T和U参数,并且T参数在0 \sim 1/(25α)范围内变化,随着Z'质量的增大,T参数的上界减小。S参数可以是正的或负的,这取决于Z'质量是大还是小。Z'质量也有上界,上界取决于T参数的值。我们得到了电弱手征拉格朗日量直到p^4阶的所有系数的值。

英文摘要:

Based on previous studies deriving the chiral Lagrangian for pseudo scalar mesons from the first principle of QCD, we derive the electroweak chiral Lagrangian and build up a formulation for computing its coefficients from one-doublet technicolor model and a schematic topcolor-assisted technicolor model. We find that the coefficients of the electroweak chiral Lagrangian for the topcolor-assisted technicolor model are divided into three parts: direct TC2 interaction part, TC1 and TC2 induced effective Z' particle contribution part, and ordinary quarks contribution part. The first two parts are computed in this paper and we show that the direct TC2 interaction part is the same as that in the one-doublet technicolor model, while effective Z' contributions are at least proportional to the p^2 order parameter β_1 in the electroweak chiral Lagrangian and typical features of topcolor-assisted technicolor model are that it only allows positive T and U parameters and the T parameter varies in the range 0\sim 1/(25α), the upper bound of T parameter will decrease as long as Z' mass become large. The S parameter can be either positive or negative depending on whether the Z' mass is large or small. The Z' mass is also bounded above and the upper bound depend on value of T parameter. We obtain the values for all the coefficients of the electroweak chiral Lagrangian up to order of p^4.

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