Comprehensive measurements of t-channel single top-quark production cross sections at √s = 7 TeV with the ATLAS detector

Abstract

This article presents measurements of the t-channel single top-quark (t) and top-antiquark (¯t) total
\nproduction cross sections σðtqÞ and σð¯tqÞ, their ratio Rt ¼ σðtqÞ=σð¯tqÞ, and a measurement of the inclusive
\nproduction cross section σðtq þ ¯tqÞ in proton-proton collisions at
\nffiffiffis
\np
\n¼ 7 TeV at the LHC. Differential
\ncross sections for the tq and ¯tq processes are measured as a function of the transverse momentum and the
\nabsolute value of the rapidity of t and ¯t, respectively. The analyzed data set was recorded with the ATLAS
\ndetector and corresponds to an integrated luminosity of 4.59 fb−1. Selected events contain one charged
\nlepton, large missing transverse momentum, and two or three jets. The cross sections are measured
\nby performing a binned maximum-likelihood fit to the output distributions of neural networks. The
\nresulting measurements are σðtqÞ ¼ 46 1ðstatÞ 6ðsystÞ pb, σð¯tqÞ ¼ 23 1ðstatÞ 3ðsystÞ pb,
\nRt ¼ 2.04 0.13ðstatÞ 0.12ðsystÞ, and σðtq þ ¯tqÞ ¼ 68 2ðstatÞ 8ðsystÞ pb, consistent with the
\nStandard Model expectation. The uncertainty on the measured cross sections is dominated by systematic
\nuncertainties, while the uncertainty on Rt is mainly statistical. Using the ratio of σðtq þ ¯tqÞ to its theoretical
\nprediction, and assuming that the top-quark-related CKM matrix elements obey the relation
\njVtbj ≫ jVtsj; jVtdj, we determine jVtbj ¼ 1.02 0.07.