2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/50158This manuscript has been withdrawn by the author. For reasons please contact Klaus Kirsten at klaus@a35.ph.man.ac.uk or kirsten@itp.uni-leipzig.de225 pages, LaTeXHigh Energy Physics - TheorySpectral functions in mathematics and physicstext