Search for $nu_mu to nu_tau$ oscillation using the $tau$ decay modes into a single charged particle.

Part of the neutrino events collected in 1994-1995 by the CHORUS experiment has been analysed. A search was performed for vτ charged current interactions followed by the τ lepton decay into a single charged negative hadron, a possible indication for vμ → vτ. oscillation. A sample of 6844 events without an identified muon has been located in the emulsion target. Within the selection criteria, no τ- candidate has been found. Combining this result with the one from the search for vτ interactions using the muonic decay mode (36 182 events with an identified muon), a 90% C.L. limit on the mixing angle sin22θμτ < 1.8 · 10-3 (at large Δm2) has been derived.