2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55234The one-loop free energy of the four-dimensional compact QED, which is known to be equivalent to the vector Sine-Gordon model, is calculated in the strong coupling regime. In the case, when the norm of the strength tensor of the saddle-point value of the corresponding Sine-Gordon model is much larger than the typical inverse area of a loop in the gas of the monopole rings, the obtained free energy decays exponentially versus this norm. In the opposite case, when the dominant configuration of the Sine-Gordon model is identically zero, the resulting free energy decays with the growth of loops as an exponent of the inverse square of their typical area.4 pages, LaTeX, no figuresHigh Energy Physics - Theorytext