2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46973Cross sections involving massive Dirac or Majorana neutrinos usually differ only by terms which are suppressed by the smallness of the neutrino mass. The process $e^+e^-\toνν$, however, is an example in which the two differential cross sections are quite distinct even in the limit $m_ν\to 0$ as long as $m_ν\not=0$. I discuss the cause of this phenomenon and comment on strategies to identify processes with quite different Majorana and Dirac neutrino signals.23 pages, RevTeX, 2 eps figures, uses epsf.styHigh Energy Physics - Phenomenologytext