Witten diagrams in momentum space and one graviton exchange between scalars in Weyl invariant unimodular gravity
Jesus Anero (Departamento de Física Teórica and Instituto de Física Teórica (IFT-UAM/CSIC), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain); Carmelo P. Martin (Universidad Complutense de Madrid (UCM), Departamento de Física Teórica and IPARCOS, Facultad de Ciencias Físicas, 28040 Madrid, Spain)
We tackle head on the computation of the -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.