Understand
Infinite sets of asymptotic soft-charges were recently shown to be related to new symmetries of the $S$-matrix, spurring a large amount of research on this and related questions.
- Notwithstanding, the raison-d'\^etre of these soft-charges rests on less firm ground, insofar as their known derivations through generalized Noether procedures tend to rely on the fixing of (gauge-breaking) boundary conditions rather than on manifestly gauge-invariant computations.
- In this article, we show that a geometrical framework anchored in the space of field configurations singles out the known leading-order soft charges in gauge theories.
- Our framework unifies the treatment of finite and infinite regions, and thus it explains why the infinite enhancement of the symmetry group is a property of asymptotic null infinity and should not be expected to hold within finite regions, where at most a finite number of physical charges -- corresponding to the reducibility parameters of the quasi-local field configuration -- is singled out.