Speaker
Description
In QCD, gluons acquire an effective mass through the Schwinger mechanism, which is triggered by the dynamical formation of longitudinally coupled massless bound-state poles. The presence of these poles leaves smoking gun signals in the fundamental Ward identities, which are displaced by contributions of the Bethe-Salpeter amplitudes of the massless bound states. This displacement can be determined by combining lattice data for the QCD propagators and vertices, and a derivative of the ghost-gluon kernel computed from a Schwinger-Dyson equation. To control the latter's truncation error, we employ lattice results directly for the transversely projected three-gluon vertex in general kinematics that contributes to the ghost-gluon kernel equation. We obtain a clearly nonvanishing displacement of the ward identity, which agrees strikingly with predictions based on the analysis of the Bethe-Salpeter equation governing the formation of the massless bound states. Our study further strengthens the evidence for the realization of the Schwinger mechanism in QCD.
