What is the simplest quantum field theory?

  title={What is the simplest quantum field theory?},
  author={Nima Arkani-Hamed and Freddy Cachazo and Jared Kaplan},
  journal={Journal of High Energy Physics},
Conventional wisdom says that the simpler the Lagrangian of a theory the simpler its perturbation theory. An ever-increasing understanding of the structure of scattering amplitudes has however been pointing to the opposite conclusion. At tree level, the BCFW recursion relations that completely determine the S-matrix are valid not for scalar theories but for gauge theories and gravity, with gravitational amplitudes exhibiting the best UV behavior at infinite complex momentum. At 1-loop… 
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