Heavy quark diffusion from the lattice

We study the diffusion of heavy quarks in the quark gluon plasma using the Langevin equations of motion and estimate the contribution of the transport peak to the Euclidean current-current correlator. We show that the Euclidean correlator is remarkably insensitive to the heavy quark diffusion coefficient and give a physical interpretation of this result using the free streaming Boltzmann equation. However if the diffusion coefficient is smaller than similar to 1/(pi T), as favored by RHIC phenomenology, the transport contribution should be visible in the Euclidean correlator. We outline a procedure to isolate this contribution.