EXPONENTIAL DECAY OF TRUNCATED CORRELATION-FUNCTIONS VIA THE GENERATING FUNCTION - A DIRECT METHOD

We consider statistical mechanics lattice models where the external fi eld dependent partition function can be represented as a standard poly mer system. Using this polymer representation and elementary complex a nalytic arguments, we obtain upper bounds and give a simple proof on t he uniform (in n) exponential decay of the n-point truncated correlati on function. We illustrate the method by applying it to the high and l ow temperature Ising model and to contour models.