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arXiv 0908.3696hep-ph
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规范对称性三族模型SU(3)_c X SU(4)_L X U(1)_X的唯象

Phenomenology of a three-family model with gauge symmetry SU(3)_c X SU(4)_L X U(1)_X

Stiven Villada, Luis A. Sanchez

摘要:

本文研究了标准模型规范群SU(3)_cXSU(2)_LXU(1)_Y到对称群SU(3)_cXSU(4)_LXU(1)_X(简称3-4-1)的推广。这个扩展提供了一个有趣的尝试来回答家庭复制的问题,在这个意义上,可以构建电弱相互作用的模型,以便通过世代之间的相互作用来实现异常消除,所有这些都是在家庭的数量必须被SU(3)_c的颜色数整除的条件下。这种异常消除方法需要一个家庭的夸克从其他两个不同的转变,从而导致树级变味中性流(FCNC)传输的两个额外的中性规范玻色子$Z'$和$Z''$的模型预测。在一个版本的3-4-1扩展,它不包含粒子与外来电荷,我们研究的费米子质谱和一些方面的现象的中性规范玻色子部门。特别是,我们施加的$Z-Z'$混合角和相应的物理新的中性规范玻色子$Z_2$的质量尺度上的限制,并建立一个下限的额外的新的中性规范玻色子$Z'' \equiv Z_3$的质量。对于分析,我们使用更新的精确电弱数据在Z极从欧洲核子研究中心LEP和SLAC线性对撞机,和原子宇称违反数据。在模型中对FCNC源的分析中,通过使用中性介子混合的最新实验输入,约束了附加的新中性规范玻色子$Z_3$的质量尺度.数据将$Z-Z'$混合角限制在O(0.001)的一个非常小的值,并且发现$M_{Z_2}$和$M_{Z_3}$的下界分别为O(1 TeV)和O(7 TeV)。

英文摘要:

We study an extension of the gauge group SU(3)_c X SU(2)_L X U(1)_Y of the standard model to the symmetry group SU(3)_c X SU(4)_L X U(1)_X (3-4-1 for short). This extension provides an interesting attempt to answer the question of family replication in the sense that models for the electroweak interaction can be constructed so that anomaly cancellation is achieved by an interplay between generations, all of them under the condition that the number of families must be divisible by the number of colours of SU(3)_c. This method of anomaly cancellation requires a family of quarks transforming differently from the other two, thus leading to tree-level flavour changing neutral currents (FCNC) transmitted by the two extra neutral gauge bosons $Z'$ and $Z''$ predicted by the model. In a version of the 3-4-1 extension, which does not contain particles with exotic electric charges, we study the fermion mass spectrum and some aspects of the phenomenology of the neutral gauge boson sector. In particular, we impose limits on the $Z-Z'$ mixing angle and on the mass scale of the corresponding physical new neutral gauge boson $Z_2$, and establish a lower bound on the mass of the additional new neutral gauge boson $Z'' \equiv Z_3$. For the analysis we use updated precision electroweak data at the Z-pole from the CERN LEP and SLAC Linear Collider, and atomic parity violation data. The mass scale of the additional new neutral gauge boson $Z_3$ is constrained by using updated experimental inputs from neutral meson mixing in the analysis of the sources of FCNC in the model. The data constrain the $Z-Z'$ mixing angle to a very small value of O(0.001), and the lower bounds on $M_{Z_2}$ and on $M_{Z_3}$ are found to be of O(1 TeV) and of O(7 TeV), repectively.

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