2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/221037We present a calculation of e^+e^- production in $γA$ reactions at MAMI and TJNAF energies within a semi-classical BUU transport model. Dilepton invariant mass spectra for $γ$C, $γ$Ca and $γ$Pb are calculated at 0.8, 1.5 and 2.2 GeV. We focus on observable effects of medium modifications of the $ρ$ and $ω$ mesons. The in-medium widths of these mesons are taken into account in a dynamical, consistent way. We discuss the transport theoretical treatment of broad resonances.42 pages including 16 figuresNuclear TheoryHigh Energy Physics - Phenomenologytext