The decay of tau leptons produced in neutrino–nucleon scatterings

Abstract

Energy and angular distributions of the τ decay products in the CERN-to-Gran Sasso ν τ appearance experiments are studied for the decay modes τ → π ν and τ → ℓ ν ¯ 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.