Mellin amplitudes for $AdS_5\times S^5$
  We revisit the calculation of holographic correlation functions in IIB supergravity on $AdS_5\times S^5$. Results for four-point functions simplify drastically when expressed in Mellin space. We conjecture a compact formula for the four-point functions of one-half BPS single-trace operators of arbitrary weight. Our methods rely on general consistency conditions and eschew detailed knowledge of the supergravity effective action. 
Leonardo Rastelli, Xinan Zhou
hep-th