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Résumé |
Extremal cubic couplings in AdS relate bulk fields such that
$\Delta_i+\Delta_j=\Delta_k$. Such couplings lead to divergent 3-point Witten
diagrams, and do not occur in theories with maximal supersymmetry. We consider the
simplest theories where such coupling are non-zero, which are string or M-theory
on singular spacetimes with fixed point loci AdS_{d+1}xS^3 for d=3,4,6, which are
dual to CFTs in d dimensions. These theories have infinite towers of graviton
modes, as well as gluon modes on the singularities. We compute the nonzero
coupling between these modes, which is in general (super)-extremal. We use these
couplings to compute the graviton exchange term in the holographic correlator of
gluon KK modes, which we match to the expected answer in the flat space limit. We
then use this graviton exchange term to compute the unmixing of the single trace
graviton modes with double traces of gluon modes, which explains the divergent 3-
point diagrams. |
