Measurement of the inclusive $t\bar{t}$ production cross section in the lepton+jets channel in $pp$ collisions at $\sqrt{s}$= 7 TeV with the ATLAS detector using support vector machines

TL;DR

This paper reports a precise measurement of the top quark pair-production cross section in proton-proton collisions at 7 TeV using support vector machines to distinguish signal from background, confirming Standard Model predictions.

Contribution

It introduces a multidimensional support vector machine classifier for top quark pair events, improving the accuracy of cross section measurement in the lepton+jets channel.

Findings

Measured cross section: 168.5 pb with uncertainties

Classifier effectively separates $t\bar{t}$ events from backgrounds

Results agree with next-to-next-to-leading order QCD predictions

Abstract

A measurement of the top quark pair-production cross section in the lepton+jets decay channel is presented. It is based on 4.6 fb$^{-1}$ of $\sqrt{s} = 7$ TeV $pp $ collision data collected during 2011 by the ATLAS experiment at the CERN Large Hadron Collider. A three-class, multidimensional event classifier based on support vector machines is used to differentiate $t\bar{t}$ events from backgrounds. The $t\bar{t}$ production cross section is found to be $\sigma_{t\bar{t}}=168.5 \pm 0.7$(stat.)$^{+6.2}_{-5.9}$(syst.)$^{+3.4}_{-3.2}$(lumi.) pb. The result is consistent with the Standard Model prediction based on QCD calculations at next-to-next-to-leading order.