Measurement of the cross section ratio σ[subscript t[bar over t]b[bar over b]]/σ[subscript t[bar over t]jj] in pp collisions at √s = 8 TeV

Apyan, Aram ; Barbieri, Richard Alexander ; Bauer, Gerry P. ; Busza, Wit ; Cali, Ivan Amos ; Chan, Matthew Hans ; Di Matteo, Leonardo ; Dutta, Valentina ; Gomez-Ceballos, Guillelmo ; Goncharov, Maxim ; Gulhan, Doga Can ; Klute, Markus ; Lai, Yue Shi ; Lee, Yen-Jie ; Levin, Andrew Michael ; Luckey, P. David, Jr. ; Ma, Teng ; Paus, Christoph M. E. ; Ralph, Duncan Kelley ; Roland, Christof E. ; Roland, Gunther M. ; Stephans, George S. F. ; Stockli, Fabian ; Sumorok, Konstanty C. ; Velicanu, Dragos Alexandru ; Veverka, Jan ; Wyslouch, Boleslaw ; Yang, Mingming ; Zanetti, Marco ; Zhukova, Victoria

Elsevier

Others  :  http://dspace.mit.edu/openaccess-disseminate/1721.1/98206

美国|英语

来源: MIT Theses in DSpace@MIT

【 摘 要 】

The first measurement of the cross section ratio σ[subscript t[bar over t]b[bar over b]/σ[subscript t[bar over t]jj] is presented using a data sample corresponding to an integrated luminosity of 19.6 fb[superscript −1] collected in pp collisions at √s = 8 TeV with the CMS detector at the LHC. Events with two leptons (e or μ) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum p[subscript T] of both 20 and 40 GeV/c . The measured ratio is 0.022 ± 0.003(stat) ± 0.005(syst) for p[subscript T]>20 GeV/c. The absolute cross sections σ[subscript t[bar over t]b[bar over b] and σ[subscript t[bar over t]jj] are also measured. The measured ratio for p[subscript T]>40 GeV/c is compatible with a theoretical quantum chromodynamics calculation at next-to-leading order.