  We analyse the flat space limit of 3-point correlators in momentum space for
general conformal field theories in even spacetime dimensions, and show they
exhibit a double copy structure similar to that found in odd dimensions. In
even dimensions, the situation is more complicated because correlators contain
branch cuts and divergences which need to be renormalised. We describe the
analytic continuation of momenta required to extract the flat space limit, and
show that the flat space limit is encoded in the leading singularity of a
1-loop triangle integral which serves as a master integral for 3-point
correlators in even dimensions. We then give a detailed analysis of the
renormalised correlators in four dimensions where the flat space limit of
stress tensor correlators are controlled by the coefficients in the trace
anomaly.

High Energy Physics - Theory;High Energy Physics - Phenomenology