標準模型之外的粒子現象學

Particle Phenomenology beyond Standard Model

蔡律行(Lu-Hsing Tsai)

指導教授 ： 何小剛

國立臺灣大學/理學院/物理研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.02709

摘要

以強作用力,弱作用力,電磁作用力相關的規範群SU(3)_C×SU(2)_L×U(1)_Y
所描述的標準模型, 解釋了自然界大部分的現象. 然而, 仍然有部
分問題無法以標準模型解釋, 像是 CP 破缺的源頭, 重子數不對稱,
弱作用尺度與蒲朗克尺度的階級差異, 強作用CP破缺, 微中子的輕
質量, 費米子家族代的數目. 在這篇論文我將集中在其中三個問題
中, 如下所列.
1. 有關CP破缺來源的主題. 為了解釋CP破缺的來源我們引進了具
有自發性CP破缺相角的多希格斯模型, 並且使這個相角在大小上等
同於夸克混合矩陣的相角, 作為CP破缺的來源. 這個假設將得到比
較簡單的湯川耦合矩陣. 我們也應用這個點子到輕子的部分. 賈斯
科不變量在PMNS矩陣可以被預測, 這可以用來區分我們所取的不同
模型.
2. 有關輕微中子質量與在翹翹板模型中希格斯衰變的主題. 與極重
右手馬由拉那微中子相關的翹翹板機制,成功的解釋輕微中子質量.
但是極重的重微中子與這個重微中子和其他粒子極微小的藕荷, 造
成驗證翹翹板理論的困難. 我們檢視在某些具有大的重輕微中子混
合矩陣的翹翹板模型中的希格斯粒子衰變, 能夠有超過標準模型20%
的增量. 接連的四體衰變也與標準模型的預測不同.
3. 有關四代費米子標準模型中的輕子味破壞的主題. 超過三代費米
子的標準模型, 例如包含四代, 也是一個可能的人選. 我們研究輕
子味破壞的過程, 像是原子中的μ-e轉換在四代費米子標準模型.
我們發現目前實驗的上界在金原子中的μ-e轉換, 能夠最緊迫地限
制相關的藕和常數. 在未來鈦原子中的μ-e轉換實驗將會得到最緊
迫的限制.

關鍵字

標準模型 ； 自發性CP破缺 ； CKM矩陣 ； PMNS矩陣 ； 翹翹板機制 ； 希格斯衰變 ； 四代的標準模型

並列摘要

The standard model (SM), which describes the gauge group SU(3)_C×SU(2)_L×U(1)_Y related to strong interaction, weak theory and electromagnetic interaction, explains most of the phenomena in the nature. However, there remain some problems which can not be explained by the SM, such as the the origin of CP violation, the baryon asymmetry of the universe, the hierarchy problem related to the weak scale and Plank scale, the strong CP problem, the light neutrino mass, and the number of fermion generations. In this thesis I will focus on three of these problems, which are
listed as follows.
1. The topic related to the source of CP violation. In order to explain the source of CP violation we introduced a multi-Higgs model with nonzero spontaneous CP violating phase, and regarded the phase, which is assumed to be identical in magnitude to the phases in quark mixing matrices, as the source of CP violation. This assumption will lead to some simpler Yukawa coupling matrices. We also applied the idea to the lepton sector. The Jarlskog invariant in PMNS matrix can be predicted, which can be used to distinguish different models we take.
2. The topic related to the light neutrino mass and Higgs decay in seesaw models. The seesaw mechanism, involving right-handed neutrinos with very large Majorana mass, explains the light neutrino masses successfully. But the too
huge mass of the heavy neutrino and the too tiny coupling with this heavy neutrino the other particles cause the difficulty in verifying the seesaw mechanism. We investigated the effect on Higgs decay in some seesaw models with large heavy-light mixing, which can increase more than 20% than that in the SM. The subsequent four body decays are also different from the prediction in SM.
3. The topic related to the lepton flavor violation in SM with four fermion generations. The SM with more than three generations, e.g., with four generations, is also a possible candidate. We studied the lepton flavor violating process
such as μ-e conversion in atoms in the SM with sequential four generations. We found that the current experimental bound on μ-e conversion with Au constrains the relevant coupling constant most stringently. The experiment on
μ-e conversion in Ti will lead to the most stringent constraint in the future.

並列關鍵字

standard model ； spontaneous CP violation ； CKM matrix ； PMNS matrix ； seesaw mechanism ； Higgs decay ； four generation standard model

參考文獻

[1] S. L. Chen, N. G. Deshpande, X. G. He, J. Jiang and L. H. Tsai, Eur. Phys. J.

[2] X. -G. He and L. -H. Tsai, Eur. Phys. J. C 71, 1598 (2011) [arXiv:1010.5204

[3] L. H. Tsai, Spontaneous CP violating phase and CKM matrix phase, Master

[4] J. -H. Chen, X. -G. He, J. Tandean and L. -H. Tsai, Phys. Rev. D 81, 113004

075021 (2010).