PHASE-TRANSITIONS AND MASS GENERATION IN 2+1 DIMENSIONS

The possibility that the f expansion can predict the order of phase tr ansitions in three-dimensional field theories is examined. For a Hermi tian matrix-valued order parameter, the epsilon expansion Predicts flu ctuation-induced first order phase transitions. We analyze two (2+1)-d imensional quantum field theories which exhibit spontaneous symmetry b reaking and have matrix order parameters. Using the large N expansion, we show that these models exhibit second order transitions and discus s the implications for the chiral-symmetry-breaking transition in (2+1 )-dimensional QCD for a critical number of quark flavors.