Measurements of the Top Quark Pair Production Cross Section in Lepton+Jets Final States using a Topological Multivariate Technique as well as Lifetime <i>b</i>-Tagging in Proton-Antiproton Collisions at √s=1.96 TeV with the D0 Detector at the Tevatron

Abstract

Two alternative measurements of the ttbar production cross section at √s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The ttbar production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields $\sigma_{p\bar{p}\rightarrow t\bar{t}+X} = 5.13^{+1.76}_{-1.57}\:{\rm (stat)}\:^{+ 0.96}_{- 1.10}\:{\rm (syst)}\:\pm 0.33\:{\rm(lumi)}\:{\rm pb}$ in the muon+jets channel, using 229.1~pb$^{-1}$, and in the combination with the electron+jets channel (226.3~pb$^{-1}$) $\sigma_{p\bar{p}\rightarrow t\bar{t}+X} = 6.60^{+1.37}_{-1.28}\:{\rm (stat)}\:^{+ 1.25}_{- 1.11}\:{\rm (syst)}\:\pm 0.43\:{\rm(lumi)}\:{\rm pb}$ . The second measurement presented reconstructs explicitly secondary vertices to do lifetime $b$-tagging. The measurement combines the muon+jets and the electron+jets channel, using 158.4~pb$^{-1}$ and 168.8~pb$^{-1}$, respectively: $\sigma_{p\bar{p}\rightarrow t\bar{t}+X} = 8.24^{+1.34}_{-1.25}\:{\rm (stat)}\:^{+1.89}_{-1.63}\:{\rm (syst)}\: \pm 0.54 \:{\rm(lumi)}\:{\rm pb}$.