On the Possibilities of Distinguishing Majorana from Dirac Neutrinos

Cross sections involving massive Dirac or Majorana neutrinos usually differ only by terms which are suppressed by the smallness of the neutrino mass. The process $e^+e^-\to\nu\nu$, however, is an example in which the two differential cross sections are quite distinct even in the limit $m_\nu\to 0$ as long as $m_\nu\not=0$. I discuss the cause of this phenomenon and comment on strategies to identify processes with quite different Majorana and Dirac neutrino signals.