Comprehensive Measurements of T-Channel Single Top-Quark Production Cross Sections at √s = 7 TeV with the ATLAS Detector


This article presents measurements of the t-channel single top-quark (t) and top-antiquark (t̅) total production cross sections σ(tq) and σ(t̅q), their ratio R_t= σ(tq) / σ(tq), and a measurement of the inclusive production cross section σ(tq+t̅q) in proton-proton collisions at √s = 7 TeV at the LHC. Differential cross sections for the tq and t̅q processes are measured as a function of the transverse momentum and the absolute value of the rapidity of t and t̅, respectively. The analyzed data set was recorded with the ATLAS detector and corresponds to an integrated luminosity of 4.59 fb⁻¹. Selected events contain one charged lepton, large missing transverse momentum, and two or three jets. The cross sections are measured by performing a binned maximum-likelihood fit to the output distributions of neural networks. The resulting measurements are σ(tq) = 46 ± 1(stat) ± 6(syst) pb, σ(t̅q )= 23 ± 1(stat) ± 3(syst) pb, R_t = 2.04 ± 0.13(stat) ± 0.12(syst), and σ(tq+t̅q) = 68 ± 2(stat) ± 8(syst) pb, consistent with the Standard Model expectation. The uncertainty on the measured cross sections is dominated by systematic uncertainties, while the uncertainty on R_t is mainly statistical. Using the ratio of σ(tq+t̅q) to its theoretical prediction, and assuming that the top-quark-related CKM matrix elements obey the relation |V_{tb} ≫ |V_{ts}|,|V_td|, we determine |V_{tb}| = 1.02 ± 0.07.



Jets (Nuclear physics), Top quark models, Leptons (Nuclear physics), Proton-proton interactions, W bosons


CC BY 3.0 (Attribution), ©2014 CERN, for the ATLAS Collaboration