OPE of the energy momentum tensor correlator in QCD

The operator product expansion (OPE) is a very usefull tool to separate the perturbative high energy physics from the low energy contributions in a controlled way. This is done by expanding the correlator of some current into a series of local operators with so-called Wilson coefficients. An important correlator is the one of the energy momentum tensor in QCD which plays an important role e.g. in sum rule approaches to glueballs and the transport and other properties of the quark gluon plasma. The focus of this talk is on the general idea of an OPE and the presentation of the results for the leading Wilson coefficient and the coefficient in front of the gluon condensate for the energy momentum tensor correlator in higher orders.