Dark Photons and Gravitino Like Particles: Complete EFT Operator Basis

Abstract: We present a more efficient method for constructing the complete EFT operator basis for particles of any mass and spin, based on on-shell method and Young tableaux. By classifying the amplitude bases according to the polarization configurations of massive particles and using their high-energy limit, our approach can construct EFT basis in a straightforward way, without need of auxiliary fields and tedious basis decomposition. Based on this improved method, we develop a Mathematica code that can automatically construct the EFT basis for particles of any spin. As applications, the EFT bases up to d=8 are explicitly constructed for dark photons and, for the first time, for spin-3/2 gravitino like particles.