Abstract:
We review various theoretical studies of 2+1 dimensional gauge and four fermion models conducted to determine their phase structures. In all these models there is a critical number of flavors up to which there is dynamical fermion mass generation and an associated global flavor symmetry breaking. We discuss various approaches to the determination of this critical number of flavors which lead to estimates ranging from 1 to 4 four component fermion flavors for QED3. These gauge theories are used as continuum approximations to condensed matter systems and the actual critical number becomes an important parameter to be determined to test the phenomenological viability of these models. We also discuss the phase structure of the model with a finite gauge boson mass.