ON THE CJT FORMALISM IN MULTIFIELD THEORIES

The issues that arise when using the Comwall-Jackiw-Tomboulis formalis m in multi-field theories are investigated. Particular attention is de voted to the interplay between temperature effects, ultraviolet struct ure, and the interdependence of the gap equations. Results are present ed explicitly in the case of the evaluation of the finite temperature effective potential of a theory with two scalar fields which has attra cted interest as a toy model for symmetry nonrestoration at high tempe ratures. The lowest nontrivial order of approximation of the Comwall-J ackiw-Tomboulis effective potential is shown to lead to consistent res ults, which are relevant for recent studies of symmetry nonrestoration by Bimonte and Lozano.