Elastic scattering of neutrinos off polarized electrons

We calculate the cross sections for elastic νl+e−→νl+e− and ν̄l+e−→ν̄l+e− scattering (l=e, μ or τ) in the Born approximation and with exactly fixed polarization states of target and final-state electrons, discussing their sensitivity to the incident (anti)neutrino flavor. We suggest investigation of the flavor composition of a (anti)neutrino beam by a flux-independent analysis of the scattering of its constituents off polarized electrons.