We tackle head-on the computation of the $s$-channel Witten diagram in momentum space corresponding to the exchange of a graviton between minimally coupled scalars in Weyl invariant unimodular gravity. By means of a lengthy calculation, we show first that the value of the diagram in question is the same as in General Relativity and, then, we obtain a compact expression for it in terms of the Mandelstam variables.
Categories: hep-th gr-qc