Limits to ν/sub μ/,ν/sub e/→ν/sub tau/ oscillations and ν/sub μ/,ν/sub e/→tau- direct coupling

We have located 3886 neutrino interactions in the fiducial volume of a hybrid emulsion spectrometer installed in the Fermilab wide-band neutrino beam. A search for tau- decays yielded no candidate, resulting in an upper limit of 0.002 (0.073) for direct coupling of ν/sub μ/ (ν/sub e/) to tau-. The ν/sub μ/ (ν/sub e/) to ν/sub tau/ limits to mass differences and mixing angles (α) between the neutrinos are at maximum mixing ΔM2<0.9 (9.0) ev2, and at maximum sensitivity sin2(2α)<0.004 (0.12). The direct-coupling limits are also used to show that most tau- decays must contain a neutral lepton other than ν/sub μ/ or ν/sub e/