Running soft theorems in effective field theory

Abstract

We study soft theorems for photons and pions with local effective field theory (EFT) corrections up to one loop order. In massive QED with a dimension-five Pauli operator, the local analytic part of the subleading soft photon theorem is renormalized by the hard integration region. On the other hand, as was previously known, the logarithmic soft terms do not receive corrections from higher-dimensional operators. We find that analogous structure appears in the double-soft pion theorem: the coefficients of logarithmic contributions are controlled entirely by the Nonlinear Sigma Model (NLSM) Lagrangian, while the Wilson coefficients of four-derivative operators in Chiral EFT appear in local subleading terms, in a form that is dictated by their RG equations.