Unexcited Electric Strings in non-Abelian Theories*

Electric fields in QED are known to discharge due to Schwinger pair production of charged particles. Correspondingly, electric fields in non-Abelian theory discharge through the production of gluons. Yet, electric flux tubes in QCD are expected to be stable against the production of charged gluons as they confine quarks. This issue was addressed in non-Abelian SU(2) gauge theory by identifying "unexcited" electric field configurations where the Schwinger process is absent. We show that similar electric field configurations, protected against quantum dissipation, exist even in SU(3) gauge theory. Motivated by the potential existence of stable QCD flux tubes, unexcited electric string solutions were recently found in SU(2) Yang-Mills-Higgs theory with a scalar in the fundamental representation. However, classical instabilities could still exist, especially since several unstable modes were previously identified in the context of homogeneous unexcited electric field configurations. In light of this, we perform a classical stability analysis of such electric string solutions.