31 Mar 2006 | Allan Adams, Nima Arkani-Hamed, Sergei Dubovsky, Alberto Nicolis, Riccardo Rattazzi
The authors argue that certain low-energy effective field theories, which appear consistent at low energies, exhibit macroscopic non-locality and cannot be embedded in a UV-complete theory whose S-matrix satisfies canonical analyticity constraints. The obstruction lies in the signs of a set of leading irrelevant operators, which must be strictly positive to ensure UV analyticity. If these signs are "wrong," it leads to superluminal fluctuations around non-trivial backgrounds, making it impossible to define local, causal evolution and implying a surprising IR breakdown of the effective theory. Such theories cannot arise in quantum field theories or weakly coupled string theories, which satisfy the usual analyticity properties. This conclusion applies to models like the DGP brane-world model and those predicting negative anomalous quartic couplings for the $W$ and $Z$. Conversely, any experimental evidence supporting these models or measuring negative signs for anomalous quartic gauge boson couplings would falsify local quantum field theory and perturbative string theory, providing evidence for superluminality and macroscopic non-locality.The authors argue that certain low-energy effective field theories, which appear consistent at low energies, exhibit macroscopic non-locality and cannot be embedded in a UV-complete theory whose S-matrix satisfies canonical analyticity constraints. The obstruction lies in the signs of a set of leading irrelevant operators, which must be strictly positive to ensure UV analyticity. If these signs are "wrong," it leads to superluminal fluctuations around non-trivial backgrounds, making it impossible to define local, causal evolution and implying a surprising IR breakdown of the effective theory. Such theories cannot arise in quantum field theories or weakly coupled string theories, which satisfy the usual analyticity properties. This conclusion applies to models like the DGP brane-world model and those predicting negative anomalous quartic couplings for the $W$ and $Z$. Conversely, any experimental evidence supporting these models or measuring negative signs for anomalous quartic gauge boson couplings would falsify local quantum field theory and perturbative string theory, providing evidence for superluminality and macroscopic non-locality.