On the stability of the Yang-Mills vacuum in the field strength approach

The Yang-Mills sector of non-abelian gauge field theories is reformulated as an effective theory in the field strength. The emerging effective action has non-trivial stationary points describing a homogeneous phase of condensed gauge bosons which corresponds to the non-perturbative vacuum. This vacuum solution is explicitly found in D=3 dimension for the gauge group SU(2). The stability of this Yang-Mills vacuum is investigated. It is found that it is stable at low energies but becomes unstable at sufficient high energies. The critical energy is basically determined by the QCD scale parameter Λ. (orig.)