One-loop Matching and Running via On-shell Amplitudes

Abstract

In this work, we put forward a straightforward and simple approach to construct the low-energy effective field theory (EFT) from a given ultraviolet (UV) full theory by integrating heavy particles out. By calculating the on-shell amplitudes, we demonstrate how to directly achieve the one-loop matching of the UV full theory onto the EFT with the complete set of independent operators in the physical basis, which are usually obtained by removing the redundant operators in the Green's basis via the equations of motion. Furthermore, taking specific examples, we explain how to implement the on-shell-amplitude approach to derive the one-loop renormalization-group equations for the Wilson coefficients, and to find out the contributions from the evanescent operators.