Causality constraints on corrections to the graviton three-point coupling

We consider higher derivative corrections to the graviton three-point coupling within a weakly coupled theory of gravity. Lorentz invariance allows further structures beyond the one present in the Einstein theory. We argue that these are constrained by causality. We devise a thought experiment involving a high energy scattering process which leads to causality violation if the graviton three-point vertex contains the additional structures. This violation cannot be fixed by adding conventional particles with spins J ≤ 2. But, it can be fixed by adding an infinite tower of extra massive particles with higher spins, J > 2. In AdS theories this implies a constraint on the conformal anomaly coefficients $$…

• UD
  U.S. Department of Energy

  Awards: DE-SC0009988, SC0009988, CSD2007-00042
• XD
  Xunta de Galicia

  Awards: GRC2013-024, CSD2007-00042