Measurement of the top quark pair production cross section with √s = 7 TeV of pp collisions at LHC with b-tagging in the dilepton final state with the ATLAS detector

We report on the measurement of the production cross section of the top quark pair in pp collision with √s = 7 TeV at LHC using 4.7 fb−1 of data taken in the ATLAS detector. The production cross section is one of the most basic properties of top quark and needed to be well understood to test the standard model of particle physics and to prepare for the future LHC physics program. The measurement is performed using the information of the b-quark jet tagging algorithm. We obtain the following cross sections in the three dilepton final states and the combined channel : σ ̄ tt = 167 ± 6 (stat.) +25/−19 (syst.) ± 3 (lumi.) pb (ee), σ ̄ tt = 178 ± 4 (stat.) +15/−11 (syst.) ± 3 (lumi.) pb (μμ), σ ̄ tt = 173 ± 3 (stat.) +16/−14 (syst.) ± 3 (lumi.) pb (eμ), and 177 ± 2 (stat.) +14/−11 (syst.) ± 3 (lumi.) pb (Combined), where (stat.), (syst.), and (lumi.) are the uncertainties from statistics, systematics other than the luminosity measurement, and the luminosity measurement, respectively. The results are consistent with the approximate NNLO prediction, 166.78+17.3/−18.4 pb. This measurement is the most precise cross section measurement in the dilepton final state in the ATLAS experiment.