Results from the NOMAD experiment

The NOMAD experiment has sought nu /sub mu / implies/implied by nu /sub tau / oscillations by looking for the emergence of tau /sup -/ in events from the CERN SPS neutrino beam. With some improvements in the techniques of analysis in relation to the results published previously and with the inclusion of data from the 1998 run, no evidence for the oscillations has been found, which results in an updated limit on the oscillation probability [P( nu /sub mu / to nu /sub tau /)<0.5* 10/sup -3/ at a 90% C.L.]. The corresponding limit on the oscillation mixing angle is given by sin/sup 2/2 theta /sub mu tau /<1.0*10/sup -3/ for large Delta m/sup 2/. By using a 1% contamination of nu /sub e/ in the neutrino beam, we can also rule out nu /sub e/ implies/implied by nu /sub tau / oscillations and constrain the probability of the relevant transition as P( nu /sub 3/ to nu /sub tau /)<3*10/sup -2/ at a 90% C.L. (sin/sup 2/2Q/sub e tau /<6*10/sup -2/ at large Delta m/sup 2/). (10 refs).