The decay of tau leptons produced in neutrino-nucleon scatterings

Energy and angular distributions of the τ decay products in the CERN-to-Gran Sasso ντ appearance experiments are studied for the decay modes τ→πν and τ→ℓν¯ν (ℓ=e or μ). We find that the decay particle distributions in the laboratory frame are significantly affected by the τ polarization. Rather strong azimuthal asymmetry of π− and ℓ− about the τ momentum axis is predicted, which may have observable consequences even at small statistics experiments.