  Charged particles in an Abelian Coulomb phase are non-local infraparticles
that are surrounded by a cloud of soft photons which extends to infinity.
Gauss' law prevents the existence of charged particles in a periodic volume. In
a $C$-periodic volume, which is periodic up to charge conjugation, on the other
hand, charged particles can exist. This includes vortices in the $3$-d
XY-model, magnetic monopoles in $4$-d $\mathrm{U}(1)$ gauge theory, as well as
protons and other charged particles in QCD coupled to QED. In four dimensions
non-Abelian charges are confined. Hence, in an infinite volume non-Abelian
infraparticles cost an infinite amount of energy. However, in a $C$-periodic
volume non-Abelian infraparticles (whose energy increases linearly with the box
size) can indeed exist. Investigating these states holds the promise of
deepening our understanding of confinement.
