The generalised infrared structure of the gluon propagator

Understand

Gauge theory correlators are potentially more singular in the infrared than those in non-gauge theories.

• We determine the implications that these singularities have on the spectrum of the theory, proving that the appearance of generalised poles implies the existence of on-shell states with fixed mass, but zero norm.
• For quantum chromodynamics these poles have direct relevance for the confinement of coloured states.
• Using lattice data for the Landau gauge gluon propagator we subsequently test for the presence of these poles, establishing that the data is indeed consistent with such a component.