CONSTRUCTION OF GRAND UNIFIED THEORIES

Systematic treatment of the theoretical and aesthetic requirements employed in the construction of unifying groups and their representations is given. Formulating the extensive set of conditions and giving reasons for them we derive a much more compact class of unified models than the one already discussed in the literature. It is shown that most models based on nonunitary groups and those with exotic representations are excluded. On the other hand, the permissible class of unitary unifying models is large but well ordered, thus making them usefull for future applications. © 1991.