2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/183941In this work we discuss the practical and conceptual issues related to quark-hadron-duality in heavy-heavy systems. Recent measurements in the charmonium region allow a direct test of quark-hadron-duality. We present a formula for non-resonant background production in e^+ e^- \to D{\bar D} and extract the resonance parameters of the ψ(3S)-ψ(6S). The obtained results are used to investigate the upsilon energy range.21 pages, 3 figures, references addedHigh Energy Physics - Phenomenologytext