臺灣博碩士論文加值系統

Tevatron 目前正在研究t''→ bW 衰變，但由於 LHC 的到來，我們必須考慮更多的能量範圍。我們討論了當b''的質量小於tW門檻時的 b''→tW(∗) 及 t(∗)W b''衰變，並討論它們在b''的質量大於tW門檻時它們是如何變成 b''→tW。我們使用了convolution 方法來做五體衰變的計算。除了CDF探討的t→bW 我們亦討論了t''→b''(∗)W(∗)。

At the Tevatron, heavy t''→ bW decay is currently being searched for, but a broader spectrum should be explored at the LHC. We discuss the two branches of b''→tW(∗) and t(∗)W for b'' below the tW threshold, and how it merges with b''→tW above threshold. We treat with convolution method and five body final state. A similar discussion is given for b''→t''(∗)W(∗) decay, and t''→b''(∗)W(∗) decay, besides the t''→bW considered by CDF.

Acknowledgement vii
Abstract 1
1 Introduction 1
1.1 The Development of Particle Physics. . . . . . . . . 1
1.2 4th Generation Standard Model. . . . . . . . . . . . 6
2 Very Heavy Quark Decays. . . . . . . . . . . . . . . . 9
2.1 Semileptonic Decay Rates . . . . . . . . . . . . . .10
2.2 Top Quark Decays . . . . . . . . . . . . . . . . . .12
2.3 Convolution Method. . . . . . . . . . . . . . . . . 16
2.4 b'' to tW. . . . . . . . . . . . . . . . . . . . . . 18
2.4.1 b''→tfifj and b→bW+W-. . . . . . . . . . . . . . 19
2.4.2 Double Counting Contradiction . . . . . . . . . . 21
2.4.3 b''5-Body Decay . . . . . . . . . . . . . . . . . 22
3 4th Generation Quarks Decays . . . . . . . . . . . . 29
3.1 Cascade Decays . . . . . . . . . . . . . . . . . . 29
3.2 Dominant b''and t''Decays . . . . . . . . . . . . . . 30
3.3 Some Assumptions . . . . . . . . . . . . . . . . . 38
3.4 b''and t''widths . . . . . . . . . . . . . . . . . . 39
4 Conclusion . . . . . . . . . . . . . . . . . . . . . 43
A Units and Dimensions. . . . . . . . . . . . . . . . . 45
B Conventions and Feynman Rules . . . . . . . . . . . . 47
B.1 Four-Vectors and Scalar Product . . . . . . . . . . 47
B.2 Dirac Gamma Matrix . . . . . . . . . . .. . . . . . 47
B.3 Trace Algebras and Tensor Contractions . . . . . . 48
B.4 Feynman Rules at Tree Level . . . . . . . . . . . . 49
B.5 Cross Sections and Decays . . . . . . . . . . . . . 50
C Phase Space Integration . . . . . . . . . . . . . . . 51
C.1 Two-Body Phase Space . . . . . . .. . . . . . . . . 51
C.2 Multiparticle Phase Space . . . . . . . . . . . . . 52
C.3 2-Body Quark Decay . . . . . . . . . . . . . . . . 53
D CKM matrix . . . . . . . . . . . . . . . . . . . . . 55

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