臺灣博碩士論文加值系統

我們發展一種新方法,稱為加權方法,可以用來區分訊號和背景,我們拿來用在美國費米實驗室的加速器環境下做分析. 我們測試此加權方法和傳統方法在尋找新粒子的衰變上.假設新粒子的質量是700 GeV衰變到兩個噴注(dijet) 的模式,而此新粒子是由質子和反質子對撞而來的. 背景事件是由NJETS這個程序所產生的.我們研究的結果發現:區分訊號和背景的效率上,加權方法的確是比傳統方法來的有效率.
之後,我們將這種加權方法應用在尋找標準模型預測下所會出現的Higgs Boson粒子.藉由p pbar * H +W/Z +X *b bbar j j + X的衰變模式來做分析. 這事件是由Pythia 7.4的事件產生程式和CTEQ2L的部分子分布方程式(Parton distribution function)產生.
我們研究發現在質心能量到達2 TeV以及積分解析度(integrated luminosity)到達33 fb^-1時,費米實驗室的加速器將有機會發現標準模型預測下的Higgs Boson粒子,如果此粒子的質量大約在140 GeV的情況下.

A new method, weighting method, has been developed to better distinguish signal from background events for the Fermilab Tevatron environment. We test the new method against the traditional cut method by searching for a hypothetic boson with mass of 700 GeV decaying in to dijets in p pbar collision. The background events are generated with NJETS program. It is found that the weighting method is more efficient than traditional slice cut method to distinguish the signal to backgrounds.
We then apply the method to search for Standard Model (SM) Higgs boson via p pbar -> H + W/Z + X -> b bbar j j + X. The event samples for this study are generated by Pythia 7.4 event generator and CTEQ2L parton distribution function.
We find that with a center of mass energy 2 TeV and an integrated luminosity of 33 fb^-1 for Tevatron Run II , the SM Higgs boson would be observable for the Higgs Mass = 120 ~ 140 GeV.

Contents
Chapter 1. Introduction
Chapter 2 Fermilab Tevatron
Chapter 3 New Particle Search in Dijet Event
Chapter 4 Search Higgs Bosob in Four-jet Events
Chapter 5 Conclusion

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