我們研究一個簡單的現象學模型，它是在大強子對撞機（LHC）中，透過一個大質量向量傳遞子生成暗扇區。暗扇區粒子可能會衰變回標準模型粒子。它實現暗物質（DM）隱藏在大強子對撞機的多個量子色動力學噴流中（類量子色動力學噴流），即所謂的半可視噴流（SVJ）。在第一部分，我們比較MLM和CKKW-L兩個噴流匹配和合併的方案；CKKW-L方案有更好的表現，並在後續的研究中使用。第二部分研究了大強子對撞機中噴流和消失的橫能量之間的運動學以及在兩個暗扇區參數下的變化，即不可視率和暗禁閉尺度，對運動學行為的影響。

We study a simple phenomenological model which is the production of the dark sector via a heavy vector mediator at the Large Hadron Collider (LHC). The dark sector may decay back to Standard Model particles. It implements that dark matter (DM) conceals within multiple QCD jets (QCD-like) at the LHC, it is so-called semi-visible jets (SVJ). In the first part, two jet matching and merging schemes, MLM and CKKW-L, are compared; the CKKW-L scheme shows better performance and is used in the later study. The second part gives a study of the kinematics of jets and missing transverse energy at the LHC. We focus on variations of two dark sector parameters, invisible rate and dark confinement scale, to the behavior of kinematics.

1 Introduction 1
2 Dark Sector Model 3
2.1 Dark sector dynamics . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 s-channel with spin-1 mediator model . . . . . . . . . . . . . . 4
2.3 Hidden valley model and semi-visible jets . . . . . . . . . . . . 5
3 Event Generation 8
4 Object and Analysis 12
4.1 Jet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Event selections . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Observable quantities . . . . . . . . . . . . . . . . . . . . . . . 14
5 Signal Features in the Truth Level 17
5.1 Implementation of CKKW-L scheme . . . . . . . . . . . . . . 17
5.2 Kinematics of varying invisible rate and dark confinement scale in the truth level . . . . . . . . . . . . . . . . . . . . . . 22
6 Conclusions 31
A Setup Tools 33
B Monte-Carlo Cross-section 36
C Multijet and Missing Transverse Momentum 37
Bibliography 43

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