在最小味破缺下之色Zee-Babu模型的輕子 味破缺過程

Lepton Flavor Violating Processes in the Colored Zee-Babu Model with Minimal Flavor Violation

劉嘯青(Siao-Cing Liou)

指導教授 ： 張維甫

國立清華大學/理學院/物理學系/博士(2016年)

摘要

我們探討色Zee-Babu模型的輕子味破缺過程，這個模型是在標準模型的框架下外加一個額外的leptoquark與一個額外的diquark。它可以給微中子質量雙圈圖的修正。在我們的工作中計算了leptoquark與diquark的衰變寬度；藉由假設diquark的湯川耦合常數在同一個數量級上以及已知diquark湯川耦合常數、leptoquark與diquark的三耦合常數、leptoquark與diquark的質量、以及微中子震盪的參數，可以導出近似的leptoquark湯耦合常數解；我們還討論了$ell o ell' gamma$分支比率、$Z o ell ell'$分支比率與它的CP破缺參數、$mu-e$轉變的分支比率。此外，我們也討論了這個模型對帶電輕子偶極矩的修正。最後在數值分析中假設同數量級的diquark湯川耦合常數以及根據最小味破缺所推論出leptoquark、右手帶電輕子、右手上夸克之間的耦合常數為零的前提下，藉由一種重新調整方法，我們預測了這個模型的以下物理量範圍：$ell o ell' gamma$分支比率、$Z o ell ell'$分支比率與CP破缺參數最大值、$mu-e$轉變的分支比率以及leptoquark衰變到帶電輕子的部分分支比率。

關鍵字

標準模型 ； 微中子質量 ； 微中子震盪 ； 色Zee-Babu模型 ； 輕子味破缺 ； CP破缺

並列摘要

e investigate the lepton flavor violating processes in the colored Zee-Babu model cite{CZBM}, which contains an extra leptoquark and an extra diquark in the standard model framework. The model has two-loop correction to the neutrino masses. In our work, the decay widths of leptoquark and diquark are calculated; by assuming that the diquark Yukawa is democratic,
%and minimal flavor violation is applied,
the Yukawa couplings of leptoquark relevant to the neutrino masses are derived approximately from the diquark Yukawa, the triple coupling, masses of leptoquark and diquark, and neutirno oscillation data; the lepton flavor violating processes $ell o ell' gamma$, $Z o ar{ell} ell'$ and its CP violation parameter, and $mu-e$ conversion are discussed in their branching ratios. Moreover, the dipole moment correction from this model to charged leptons is discussed. In the numerical study, by using a rescaling method, the predicted regions for the branching ratios of $ell o ell' gamma$, $Z o ar{ell} ell'$, and $mu-e$ conversion, maximum of the CP violation parameters in $Z o ell ell'$, as well as the partial branching ratios for the decays of leqtoquark to a charged lepton and a up-type quark are found under the assumption: democratic diquark Yukawa and minimal flavor violation which leads the couplings between leptoquark, both right-handed charged leptons and up-type quarks to zeros.

並列關鍵字

standard model ； neutrino mass ； neutrino oscillation ； colored Zee-Babu model ； leptoquark ； diquark ； lepton flavor violating processes ； CP violation

參考文獻

[3] E. Fermi, Z.Phys. 88 (1934) 161-177.

[5] S. Weinberg, Phys. Rev. Lett. 43 (1979) 1566.

[6] N. Cabibbo, Phys. Rev. Lett. 10, 531 (1963).

[7] M. Kobayashi and T. Maskawa, Prog. Theor. Phys. 49, 652 (1973).

[9] J. N. Bahcall, R. Davis, Jr., Science 191 (1976) 264-267.