A more sensitive search for neutrino(muon) to neutrino(tau) oscillations in NOMAD

With additional data and improved algorithms, we have enhanced the sensitivity of our appearance search for nu(mu) to nu(tau) oscillations in the NOMAD detector in the CERN-SPS wide-band neutrino beam. The search uses kinematic criteria to identify charged current interactions followed by decay of the tau to one of several decay modes. Our ‘‘blind’’ analyses of deep-inelastic scattering data taken in 1996 and 1997, combined with consistent reanalyses of previously reported 1995 data, yield no oscillation signal. For the two-family oscillation scenario, we present the contour outlining a 90% C.L. confidence region in the oscillation parameters 3.5 times more stringent than in our previous publication.