Direct Search for Charged Higgs Bosons in Decays of Top Quarks

We present a search for charged Higgs bosons in decays of pair-produced top quarks in $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence for signal, we exclude most regions of the ( $M_{H^{\pm }},\tan \beta$) parameter space where the decay $t\to {\mathrm{H}}^{+}b$ has a branching fraction $>0.36\mathrm{}$ and $B(H^{\pm }\to \tau {\nu }_{\tau })$ is large.