Search for charged Higgs boson decays of the top quark using hadronic τ decays

We present the result of a search for charged Higgs boson decays of the top quark, produced in p{bar p} collisions at {radical}s = 1.8 TeV. When the charged Higgs boson is heavy and decays to a {tau} lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity {tau}. Data collected in 1992 and 1993 at the Collider Detector at Fermilab, corresponding to 18.7 {+-} 0.7 pb{sup -1}, exclude new regions of combined top quark and charged Higgs boson mass, in extensions to the standard model with two Higgs doublets.