Combination of tt̄ cross section measurements and constraints on the mass of the top quark and its decays into charged Higgs bosons

We combine measurements of the top quark pair production cross section in pp̄ collisions in the jets, and τ final states (where is an electron or muon) at a center of mass energy of s=1.96TeV in 1fb-1 of data collected with the D0 detector. For a top quark mass of 170GeV/c2, we obtain σtt̄=8.18-0.87+0.98pb in agreement with the theoretical prediction. Based on predictions from higher order quantum chromodynamics, we extract a mass for the top quark from the combined tt̄ cross section, consistent with the world average of the top quark mass. In addition, the ratios of tt̄ cross sections in different final states are used to set upper limits on the branching fractions B(t→H+b→τ+νb) and B(t→H+b→cs̄b) as a function of the charged Higgs boson mass. © 2009 The American Physical Society.