2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/41619The \bar{nu}e^- --> pi^- pi^0 and nu e^+ --> pi^+ pi^0 reaction have a resonant structure whenever the energy of the s--channel equals the mass of a J^P=1^- vector meson. The resonant cross sections are of the order 10^{-38} cm^2 and correspond to cosmic ray antineutrino energies in the range 0.2 to 2 TeV. A similar structure occurs in the annihilation of cosmic ray antineutrinos with a relic (background) neutrino. For m_{nu} <= 10^{-3} eV the resonant energy is above GZK limit and their decay products include multiple gamma--rays. Possible detection schemes are discussed, especially those which rely on Cherenkov radiation.The paper uses FEYNMAN package for generating feynman diagrams in latex. Two references are added in version 2High Energy Physics - Phenomenologytext