Comprehensive measurements of \(t\)-channel single top-quark production cross sections at \(\sqrt{s} = 7\) TeV with the ATLAS detector

Abstract

This article presents measurements of the \(t\).channel single top-quark \(t\) and top-antiquark \(\bar{t}\) total production cross sections \(\sigma(tq)\) and \(\sigma(\bar{t}q)\). their ratio \(R_{t}=\sigma(tq)/\sigma(\bar{t}q)\). and a measurement of the inclusive production cross section \(\sigma(tq + \bar{t}q)\) in proton--proton collisions at \(\sqrt{s} = 7\).TeV at the LHC. Differential cross sections for the \(tq\) and \(\bar{t}q\) processes are measured as a function of the transverse momentum and the absolute value of the rapidity of \(t\) and \(\bar{t}\). 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 \(\sigma(tq)= 46\pm 6\; \mathrm{pb}\). \(\sigma(\bar{t}q)= 23 \pm 4\; \mathrm{pb}\). \(R_{t}=2.04\pm 0.18\). and \(\sigma(tq + \bar{t}q)= 68 \pm 8\; \mathrm{pb}\). 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 \(\sigma(tq + \bar{t}q)\) to its theoretical prediction, and assuming that the top-quark-related CKM matrix elements obey the relation \(|V_{tb}|\gg |V_{ts}|, |V_{td}|\). we determine \(|V_{tb}|=1.02 \pm 0.07\).