Fundamental and effective SU(2) Yang-Mills vertices

Calorons and plane waves within and in between them {\sl collectively} give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum of deconfining SU(2) Yang-Mills thermodynamics (dynamical gauge-symmetry breaking). In the present talk we discuss the role of a {\sl single} caloron in inducing effective local vertices, characterized by powers of $\hbar$, mediating the interaction of plane waves which propagate over large distances. The constraints on momentum transfers through effective 4-vertices are revisited.