2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194698Particles with millicharge q and sub-eV mass can be produced in photon-photon collisions, distorting the energy spectrum of the Cosmic Microwave Background. We derive the conservative bound q < 10^-7 e (as well as model-dependent bounds two orders of magnitude stronger), incompatible with proposed interpretations of the PVLAS anomaly based on millicharged production or on millicharged-mediated axion-like couplings.7 pages, 2 figures. Final versionHigh Energy Physics - Phenomenologytext