  A gauge-invariant saddle point expansion for the Yang-Mills vacuum transition
amplitude on the basis of the squeezed approximation to the vacuum wave
functional is outlined. This framework allows the identification of
gauge-invariant infrared degrees of freedom which arise as dominant sets of
gauge field orbits and provide the principal input for an essentially
analytical treatment of soft amplitudes. The analysis of the soft modes sheds
new light on how vacuum fields organize themselves into collective excitations
and yields a gauge-invariant representation of instanton and meron effects as
well as a new physical interpretation for Faddeev-Niemi knots.

High Energy Physics - Theory