A measurement of the production cross section for top quark pairs (tt) in pp collisions at √s = 7 TeV is presented using data recorded with the ATLAS experiment at the Large Hadron Collider in 2010. Events are selected in the tt semileptonic decay channel by requiring a single lepton (electron e or muon μ), large missing transverse energy and at least four jets. In a data sample of 35:3 pb⁻¹, 396 e + jets events and 653 μ + jets events are observed. A multivariate top likelihood is built from four variables including a b-tagging variable. A fit to the top likelihood distribution is employed to extract the tt cross section separately in the e+ jets and μ + jets channel. A combined fit to the top likelihood distribution in both channels is employed to extract a combined cross section. The tt cross section, assuming a top mass of 172.5 GeV, is found to be: e + jets channel: σ(u) = 164.4^+16.2(-15.4)(stat)^31.2(-36.2)(syst)^5.8(-5.4)(lumi) pb; μ + jets channel: σ(u) = 167.8^+1.3.9(-13.4)(stat)^3.9(-34.8)(syst)^5.9(-5.5)(lumi) pb; e + jets and μ + jets channel combined: σ(u) = 166.4^+10.5(-10.2)(stat)^31.7(-33.6)(syst)^5.9(-5.5)(lumi) pb The measurement agrees with approximate NNLO perturbative QCD calculations.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/202932 |
| Date | January 2011 |
| Creators | Lei, Xiaowen |
| Contributors | Johns, Kenneth, Cheu, Elliott, Fang, Li-Zhi, Su, Shufang, Wing, William, Johns, Kenneth |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Electronic Dissertation |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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