2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/122619Applying the unitary clothing transformation method in the model of charged spinless nucleons and neutral mesons interacting via the three-linear Yukawa-type coupling, the expression for the charge shift in the third order in the coupling constant is derived. Being determined off the energy shell, the ex-pression can be reduced on the energy shell to the explicitly covariant form, providing the independence of the particle momenta. Comparison with the cor-responding result of the Dyson covariant perturbation theory is performed by es-tablishing the link between the old-fashioned perturbation theory and the cloth-ing approach.59 pages, 2 figures, master thesisNuclear Theorytext