Search for vμ → vτ oscillation using the τ decay modes into a single charged particle

Abstract Part of the neutrino events collected in 1994-1995 by the CHORUS experiment has been analysed. A search was performed for ν τ charged current interactions followed by the τ lepton decay into a single charged negative hadron, a possible indication for ν μ →ν τ 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 ν τ interactions using the muonic decay mode (36 182 events with an identified muon), a 90% C.L. limit on the mixing angle sin 2 2 θ μτ −3 (at large Δm 2 ) has been derived.