2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/156657We use the semiclassical method proposed in \cite{Adelcio2003} to study scalar products such as the overlap, Husimi functions and fidelity decay. Scars of classical periodic orbits arise naturally in this pertubative expansion. We also derive analytically a well known numerical result that fidelity has a quadratic decay for short times. We study the overlap in the chaotic regime and integrable for some simple systems.24 pages, 12 figuresQuantum Physicstext