We present a formalism for local composite operators. The corresponding
effective potential is unique, multiplicatively renormalizable, it is the sum
of 1PI diagrams and can be interpreted as an energy-density. First we apply
this method to λΦ4 theory where we check renormalizability up to
three loops and secondly to the Coleman-Weinberg model where the gauge
independence of the effective potential for the local composite operator
ϕϕ∗ is explicitely checked up to two loops.Comment: 20 page