Final NOMAD results from on νμ → ντ and νe → ντ oscillations including a new search for ντ appearance using hadronic τ decays

Results from the ντ appearance search in a neutrino beam using the full NOMAD data sample are reported. A new analysis unifies all the hadronic τ decays, significantly improving the overall sensitivity of the experiment to oscillations. The “blind analysis” of all topologies yields no evidence for an oscillation signal. In the two-family oscillation scenario, this sets a 90% CL allowed region in the sin2 2θμτ –_m2 plane which includes sin2 2θμτ < 3.3 × 10−4 at large _m2 and _m2 < 0.7 eV2/c4 at sin2 2θμτ = 1. The corresponding contour in the νe →ντ oscillation hypothesis results in sin2 2θeτ < 1.5 × 10−2 at large _m2 and _m2 < 5.9 eV2/c4 at sin2 2θeτ = 1. We also derive limits on effective couplings of the τ lepton to νμ or νe.