Measurement of the top quark pair production cross section in pp̅ collisions

We present a measurement of the tt production cross section in pp collisions at √s=1.8TeV by the D0 experiment at the Fermilab Tevatron. The measurement is based on data from an integrated luminosity of approximately 125pb -1 accumulated during the 1992–1996 collider run. We observe 39 tt candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7±2.2 events. For a top quark mass of 173.3GeV/c 2 , we measure the tt production cross section to be 5.5±1.8pb.