Asymptotic Symmetries of Yang-Mills with Theta Term and Monopoles

TL;DR

The paper investigates how asymptotic YM symmetries with singular large gauge transformations at null infinity can correspond to bulk monopole-like structures and how a theta term induces a decoupling between holomorphic and antiholomorphic boundary currents, akin to 2D WZW/Chern–Simons dynamics. It explicitly demonstrates monopole encoding in the Abelian Maxwell case and shows that the non-Abelian theta term can separate boundary current algebras at special theta values, suggesting a boundary theory with WZW-like features. These results connect soft-theorem–driven asymptotic symmetries to bulk topology and boundary conformal-like structures, with implications for holography and CP violation in YM theories.

Abstract

In this short note we suggest that the singular behavior of large gauge transformations preserving the vacuum at null infinity in Yang-Mills theory implies monopoles into the bulk, as well as that the inclusion of a theta term induces a decoupling between holomorphic and anti-holomorphic currents associated to those large gauge transformations