A brief Introduction to Dispersion Relations and Analyticity

Abstract

In these lectures we provide a basic introduction into the topic of dispersion relation and analyticity. The properties of 2-point functions are discussed in some detail from the viewpoint of the Källén-Lehmann and general dispersion relations. The Weinberg sum rules figure as an application. The analytic structure of higher point functions in perturbation theory are analysed through the Landau equations and the Cutkosky rules.

Comments: 28 pages, 11 figures, Lectures given at Dubna School: "Strong Fields and Heavy Quarks", July 2016