Color Memory

TL;DR

This work establishes a Yang-Mills analogue of gravitational memory by showing that color flux through ${\cal I}^+$ induces a nontrivial large gauge transformation that shifts the final flat connection relative to the initial one, causing two quarks initially in a color singlet to acquire a relative color rotation. The authors derive a nonlinear PDE for the large gauge transformation $U(z,\bar z)$ on the celestial sphere and solve it perturbatively in the color flux, obtaining a leading term that matches the Fourier transform of the soft gluon theorem and a finite nonlinear correction at higher order. The results connect asymptotic symmetries, vacuum degeneracy of flat connections, and soft theorems in nonabelian gauge theory, enriching the memory effect paradigm beyond gravity and abelian theories with potential implications for high-energy color flux phenomena. They also hint at deep links to the structure of vacua on null infinity and may inform future experimental or phenomenological explorations at energy scales above confinement.

Abstract

A transient color flux across null infinity in classical Yang-Mills theory is considered. It is shown that a pair of test `quarks' initially in a color singlet generically acquire net color as a result of the flux. A nonlinear formula is derived for the relative color rotation of the quarks. For weak color flux the formula linearizes to the Fourier transform of the soft gluon theorem. This color memory effect is the Yang-Mills analog of the gravitational memory effect.