尋找與W玻色子共同產生之單一頂夸克

Abstract

The CMS (Compact Muon Solenoid) experiment is located at the LHC (Large Hardon Collider) proton-proton collider in CERN. The center of mass energy of the proton-proton collider is 14 TeV. The experiment plans to start taking data at early 2008.

Besides the pair top quark production observed by CDF (The Collider Detector at Fermilab) and D0 (DZero), the Standard Model also allows single top quark production which we expect to observe in the LHC with the CMS detector. The single top is produced by electroweak interaction and this gives us a window to directly measure the CKM (Cabbibo-Kobayashi-Maskawa) matrix element |Vtb| since the production cross section is proportional to jVtbj2. Assuming three quark generations or unitarity of the CKM matrix can imply |Vtb|~1. However, if the fourth generation exists, |Vtb| can be any number smaller then 1. There are three modes of single top production: (1) t-channel, (2) s-channel, and (3)W associated production or tW. Based on Monte Carlo simulation, a study of cross section and significance of tW production in the CMS experiment is presented in this thesis.