利用緊湊渺子線圈搜尋第四世代下型夸克

Abstract

這篇論文發表了尋找新的下型夸克的結果，我們利用緊湊渺子線圈蒐 集大強子對撞機製造的7TeV質子對撞資料加以分析。 假設新型夸克b0會衰變成頂夸克以及W波色子，成對生成的新夸克有機會出現三個或兩個同電荷的帶電輕子，我們利用這個特性來辨識新型夸克。結果並沒有觀測到明顯的新物理，我們推測新夸克的質量應該 611GeV 以上，這個觀測的信心水準是95%。

Results are presented from a search for heavy bottom-like quarks, pair-produced in pp collisions at a center of mass energy of 7 TeV, undertaken with the CMS experiment at the LHC. The b0 quarks are assumed to decay exclusively to tW. The pair production process of b0 can be identified by its distinctive signatures of three leptons or two leptons of same charge, and at least one b-quark jet. Using a data sample corresponding to an integrated luminosity of 4.9 fb −1, observed events are compared to the standard model background predictions, and the existence of b0 quarks having masses below 611 GeV is excluded at 95% confidence level.