Conformality of non-conformal correlators

Abstract

We show that position space correlators of a Poincare invariant quantum field theory can be recast in terms of conformally invariant correlators, in other words, as functions of conformal cross ratios. In particular, we show that correlators of massless fields in flat spacetimes with $n-$point interactions can be expressed as position space soft limits of conformally invariant correlators with $(n+1)-$point interactions. We show that this correspondence applies at the level of every Feynman diagram that appears in the perturbative expansion of the correlators in the respective coupling constants. We apply this method to find exact answers for some Feynman diagrams including several loop examples. We also show that the analogous correlators for massive fields can be expressed as infinite sums of conformal correlators.