期刊
JOURNAL OF HIGH ENERGY PHYSICS
卷 -, 期 10, 页码 -出版社
SPRINGER
DOI: 10.1007/JHEP10(2012)110
关键词
NLO Computations; Hadronic Colliders
资金
- SNSF
We present details of a calculation of the cross section for hadronic top-antitop production in next-to-leading order (NLO) QCD, including the decays of the top and antitop into bottom quarks and leptons. This calculation is based on matrix elements for nu(e+)(e)mu(-)(nu) over bar (mu)b (b) over bar production and includes all non-resonant diagrams, interferences, and off-shell effects of the top quarks. Such contributions are formally suppressed by the top-quark width and turn out to be small in the inclusive cross section. However, they can be strongly enhanced in exclusive observables that play an important role in Higgs and new-physics searches. Also non-resonant and off-shell effects due to the finite W-boson width are investigated in detail, but their impact is much smaller than naively expected. We also introduce a matching approach to improve NLO calculations involving intermediate unstable particles. Using a fixed QCD scale leads to perturbative instabilities in the high-energy tails of distributions, but an appropriate dynamical scale stabilises NLO predictions. Numerical results for the total cross section, several distributions, and asymmetries are presented for Tevatron and the LHC at 7TeV, 8TeV, and 14TeV.
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