Gravitational effective field theory islands, low-spin dominance, and the four-graviton amplitude

Abstract We analyze constraints from perturbative unitarity and crossing on the leading contributions of higher-dimension operators to four-graviton amplitude in four spacetime dimensions, including that follow distinct helicity configurations. focus leading-order effect due exchange by massive degrees freedom which makes amplitudes interest infrared finite. In particular, we place a bound coefficient R 3 operator corrects graviton three-point terms 4 coefficient. To test obtain nontrivial effective field-theory data computing taking large-mass expansion one-loop minimally-coupled with particles up spin 2 circulating loop. Remarkably, observe EFT coefficients obtained both string lie small islands. The shape location islands can be derived dispersive representation for Wilson using assuming lowest-spin spectral densities are largest. Our analysis suggests weakly-coupled gravitational physical theories much more constrained than indicated bounds arising considerations → scattering. used computed modern methods, generalized unitarity, supersymmetric decompositions double copy.