OPERATOR PRODUCT EXPANSION AT FINITE-TEMPERATURE

We extend an earlier, configuration space method to find the Wilson co efficients of operators appearing in the short distance expansion of t hermal correlation functions of different quark bilinears. Considering all the different correlation functions, there arise, up to dimension four, two new operators, in addition to the two appearing already in the vacuum correlation functions. They would contribute substantially to the QCD sum rules, when the temperature is not too low. (C) 1998 Pu blished by Elsevier Science B.V.