Search for Charged Higgs Bosons in Decays of Top Quark Pairs

We present a search for charged Higgs bosons in decays of pair-produced top quarks using $109.2\pm 5.8{\mathrm{pb}}^{-1\mathrm{}}$ of data recorded from $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ by the D0 detector during 1992–1996 at the Fermilab Tevatron. No evidence is found for charged Higgs production, and most parts of the $[M_{H^{+}},\tan \beta ]$ parameter space where the decay $t\to H^{+}b$ has a branching fraction close to or larger than that for $t\to W^{+}b$ are excluded at $95\%$ confidence level. Assuming $m_t=175\mathrm{}\mathrm{GeV}$ and $\sigma (p\overline{p}\to t\overline{t})=5.5\mathrm{}\mathrm{pb}$, for $M_{H^{+}}=60\mathrm{}\mathrm{GeV}$, we exclude $\tan \beta <0.97\mathrm{}$ and $\tan \beta >40.9\mathrm{}$.