2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/47168We show that the conventionally defined partonic cross section for the production of isolated prompt photons is not an infrared safe quantity. We work out the case of $e^+e^- \to γ+ X$ in detail, and we discuss implications for hadron reactions such as $p \bar{p} \to γ+ X$.8 pages, latex2e, 2 figures, uses Moriond.sty; Invited paper presented by E. L. Berger at the XXXIInd Rencontres de Moriond, QCD and High Energy Hadronic Interactions, Les Arcs, Savoie, France, March 22 - 29, 1997High Energy Physics - Phenomenologytext