Measurement of the top-antitop production cross section in proton-antiproton collisions at center of mass energy = 1.96 TeV.

Abstract

The direct observation of the top quark was first achieved at the Tevatron proton anti-proton collider at Fermilab. This discovery completed the third generation quark sector where the top quark is expected to accompany the bottom quark in the weak isospin doublet. This dissertation will discuss the experimental verification of the production cross section as predicted by the Standard Model. A measurement of the <italic>tt&macr;</italic> production cross section using 107.9 <italic>pb</italic><super>-1</super> of <italic>pp&macr; </italic> collisions at s = 1.96 TeV collected with the Collider Detector at Fermilab between March of 2003 and June of 2003 is presented. The measurement focuses on the <italic> tt&macr;</italic> production in the lepton plus jets final state in which one of the W bosons from the <italic>tt&macr;</italic> decay subsequently decays leptonically to an electron or a muon, and the other decays hadronically. The B-tagging technique which utilizes the precision silicon detector tracking is used to enhance the signal for <italic>tt&macr;</italic> events relative to the background through identification of the bottom quark from its measurable lifetime. The <italic>tt&macr;</italic> production cross section is measured to be sigma<italic>_tt&macr;</italic> = 4.5 +/- 1.4 (stat) +/- 0.8 (sys) pb.