Study of top-quark pair cross-section measurement in the dilepton channel with the ATLAS detector at the LHC

A study of the production cross-section measurement of top-quark pair in the dilepton channel at the Large Hadron Collider (LHC) with the ATLAS experiment at a centre-of-mass energy of sqrt(s)=10 TeV and for a data amount of L=200pb−1 is presented. This study in- vestigates the performance of the cross-section measurement with a cut-and-count analysis on Monte Carlo simulated samples. A full list of systematic uncertainties is investigated and finally combined with the statistical uncertainties in a likelihood to extract the combined uncertainty. The combined sensitivity of the analysis in all dilepton decay-channels is a relative uncertainty on the cross-section mea- surement of: Delta sigma/sigma combined [%] = +-3.1(stat)+9.6-8.7(syst)+26.2-17.4(lumi) Finally the study is compared to the same analyses performed at different centre-of-mass energies of 14GeV and 7GeV and two dilepton tt-pair event candidates in 280pb-1 are presented.