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High Energy Physics - Theory, hep-th
Abstract:
We study the implications of scale invariance in four-dimensional quantum
field theories. Imposing unitarity, we find that infinitely many matrix
elements vanish in a suitable kinematical configuration. This vanishing is a
nontrivial necessary condition for conformality. We provide an argument why
this is expected to be a sufficient condition as well, thereby linking scale
and conformal invariance in unitary theories. We also discuss possible
exceptions to our argument.