Heavy Dirac and Majorana neutrino production ine + e − collisions

The production of heavy Dirac and Majorana neutrinos ine ⁺ e ^? collisions is investigated. The heavy Dirac and/or Majorana neutrinos can be produced in charged and neutral current processes $(e^ + e^ - \to N_1 \bar N_2 )$ . The production of a single heavy neutrino is possible if it mixes with the light neutrino species. The production of heavy neutrinos in Higgs channels is also studied, since in some specific models the Yukawa couplings could be large enough to make the production of heavy neutrinos through Higgs boson exchanges sufficiently large for detection. The most general left-right symmetric model with possibly complexV orA couplings is used in the analytic calculations of the production cross sections, but the numerical examples are given using simplified left-right symmetric model. The interference terms between different production channels have been studied in great detail and in some cases the interference terms are found to be non-negligible in wide range of production spectrum. The pair production cross section is larger in the Dirac case than it is in the Majorana case, but the single heavy Majorana neutrino production cross section is roughly twice as large as that of a Dirac neutrino.