2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/149161In Yang-Mills theory massless point sources lead naturally to shock-wave configurations. Their magnetic counterparts endow the vacuum of the four-dimensional compact abelian model with a Coulomb-gas behaviour whose physical implications are briefly discussed. (Contribution to ``Quark Confinement and the Hadron Spectrum'', Como 20-24 June 1994. Revised version.)7 pages, latex, no figuresHigh Energy Physics - TheoryCondensed MatterHigh Energy Physics - Latticetext