  We discuss the problem of regularizing correlators in conformal field
theories. The only way to do it in coordinate space is to interpret them as
distributions. Unfortunately except for the simplest cases we do not have
tabulated mathematical results. The way out we pursue here is to go to momentum
space and use Feynman diagram techniques and their regularization methods. We
focus on the energy-momentum tensor correlators and, to gain insight, we
compute and regularize 2-point functions in 2d with various techniques both in
coordinate space and in momentum space, obtaining the same results. Then we do
the same for 2-point functions in 4d. Finally we turn to 3-point function in
4d, and concentrate on the parity-odd part. We derive in particular the
regularized trace and divergence of the energy-momentum tensor in a chiral
fermion model. We discuss the problems related to the parity-odd trace anomaly.
