RENORMALIZATION-GROUP APPROACH TO FIELD-THEORY AT FINITE-TEMPERATURE

Scalar field theory at finite temperature is investigated via an impro ved renormalization group prescription which provides an effective res ummation over all possible nonoverlapping higher loop graphs. Explicit analyses for the lambda phi(4) theory are performed in d = 4 Euclidea n space for both low and high temperature limits. We generate a set of coupled equations for the mass parameter and the coupling constant fr om the renormalization group how equation. Dimensional reduction and s ymmetry restoration are also explored with our improved approach.