Possible existence of "hot-sector generations" above the well known 3 generation bound is investigated on the basis of a model of leptons and quarks, which is based on the Harari and Shupe's one. Our model predicts the existence of { \bf3 + 1} generations above the ordinary "cold-sector" 3 generations. Majorana neutrinos are introduced to realize the heavy neutrino masses in hot-sector generations. Properties of heavy neutrinos are also discussed.
Categories: hep-ph