2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/94578The paper discusses the Berry phase influence on the weak localization phenomenon at the adiabatic backscattering of ultrarelativistic particles in a random medium. We demonstrate that bosons that pass along a certain closed path in opposite directions come back always in phase (an example: the backscattering enhancement of electromagnetic waves), whereas fermions come exactly in antiphase. This produces a "complete weak antilocalization" of ultrarelativistic fermions: the backscattering field intensity vanishes.5 pages, 3 figures, to appear in Physics Letters AOpticsDisordered Systems and Neural NetworksQuantum Physicstext