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We argue that a theoretical upper bound exists on the cutoff of any effective theory that describes an electromagnetically interacting massive higher spin field in at space. The cutoff is a simple function of the particle's mass, spin and electric charge, and cannot be arbitrarily high. In the spirit of effective field theory, this bound is independent of any possible UV completion of the theory, such as string theory. A systematic study to quantify the degree of singularity of the massless limit is made with the help of the Stüuckelberg formalism. For spin 2, we find that the cutoff upper bound is Λ 2 ∼ me -1/3 . By demonstrating the existence of cohomological obstructions and presenting arguments involving physical processes, we prove that indeed the cutoff cannot be higher. We show that the existence of a cutoff is connected to other pathologies of the system, such as the Velo-Zwanziger acausality. In particular, we argue that, for a judicious choice of non-minimal interaction terms, the pathologies of the spin 2 system appear, at least in the scalar sector, in a regime where we can no longer trust our effective field theory description. We also suggest that a completely pathology-free theory may be expected to have a cutoff much lower than the estimated upper bound. As an explicit example of a consistent theory, we consider the Argyres-Nappi Lagrangian, that indeed exhibits a much smaller cutoff. For spin 3/2, which is found to have a maximum cutoff of Λ 3/2 ∼ m /[Special characters omitted.] <math> <f> <rad><rcd>e</rcd></rad></f> </math> , we conjecture about how to construct a consistent theory without introducing dynamical gravity. We generalize the results to arbitrary integer and half-integer spins to find that the cutoff upper bound is given by Λ s ∼ me-1/(2 s-1) . We briefly discuss on how causality constraints in external background fields may give stronger model-independent bounds on the UV cutoff, and how one can use these techniques to study gravitational or other interactions of the high spin field.
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