QCD effective action and stability of magnetic condensation

Axially-symmetric stationary solutions in a pure SU(3) QCD

“…Solutions determined by the boundary conditions (15) correspond to regular single-valued functions. Since the fields K i (r, θ, t) represent components of the gauge potential which are not physical observables (unless the color symmetry is broken), one can choose boundary conditions with multi-valued intial profile functions as well.…”

“…It was shown that the vacuum is unstable due to presence of a tachyonic unstable mode [25]. In subsequent studies several vacuum models have been proposed with various implemented vacuum field configurations: the vortices [7][8][9][10][11], center vortices [12][13][14], monopoles [15][16][17], dyons [18] etc. Recently it has been proposed that regular stationary spherically symmetric monopole and axially symmetric monopole-like solutions are stable under the vacuum gluon fluctuations at microscopic space-time scale [19,20].…”