Neutrino oscillation searches at CHORUS

CHORUS searches for nu /sub mu / to nu /sub tau / oscillations in the CERN wide band neutrino beam. The experiment has been taking data from 1994 until 1997. A fraction of the events collected in 1994 has been located in the emulsion target and a dedicated search for nu /sub tau / charged current interactions has been performed in the mu /sup -/ nu /sub mu / nu /sub tau / and h/sup -/(nh/sup 0/) nu /sub tau / decay channels of the tau lepton. No candidates for nu /sub tau / charged current interactions have been found. A limit on the mixing angle of sin/sup 2/2 theta /sub mu tau /<4.5.10/sup -3/ at 90% C.L. for large Delta m/sup 2/ values can be set, which improves the previous best result. (4 refs).