New results on the $\nu_{\mu}\to \nu_{\tau}$ oscillation search with the CHORUS detector

The present results on the nu /sub mu / to nu /sub tau / oscillation search by the CHORUS experiment at CERN are summarized. A fraction of the neutrino interactions collected in 1994-1997 has been analysed, searching for nu /sub tau / charged current interactions followed by the tau lepton decay into a negative hadron, electron, or into a muon. A sample of 126, 229 events with an identified muon in the final state and 19,436 events without an identified muon in the final state have been located in the emulsion target. Within the applied cuts, no nu /sub tau / candidate has been found. This result leads to a 90% C.L. limit P( nu /sub mu / to nu /sub tau /)4.0<.10/sup -4/ on the mixing probability. A nu /sub e/ to nu /sub tau / result is also presented corresponding to 90% C.L. limit on the mixing probability of P( nu /sub e/ to nu /sub tau /)<3.0.10/sup -2/. (8 refs).