Trends in Grand Unification: unification at strong coupling and composite models

Abstract

We review several problems of conventional Grand Unification and some new approaches. In particular, we discuss strongly coupled Grand Unified Theories. Standard Model may emerge as a low energy effective theory of composite particles in these models. We construct a realistic model of this kind.

Comments: 14 pages, 2 eps figures. Lecture at the Baksan School ``Particles and Cosmology'', Baksan Valley, April 19 - 25, 1999