The Structure of Quasi-Real and Virtual Photons

This review covers the measurements of the QED and QCD structure of quasi-real and virtual photons from the reaction ee --> ee gamma* gamma(*) --> ee X.Comment: Invited talk given at the PHOTON 99 Conference, Freiburg, Germany, May 1999, to appear in the Proceeding

The Stueckelberg Field

In 1938, Stueckelberg introduced a scalar field which makes an Abelian gauge theory massive but preserves gauge invariance. The Stueckelberg mechanism is the introduction of new fields to reveal a symmetry of a gauge--fixed theory. We first review the Stueckelberg mechanism in the massive Abelian gauge theory. We then extend this idea to the standard model, stueckelberging the hypercharge U(1) and thus giving a mass to the physical photon. This introduces an infrared regulator for the photon in the standard electroweak theory, along with a modification of the weak mixing angle accompanied by a plethora of new effects. Notably, neutrinos couple to the photon and charged leptons have also a pseudo-vector coupling. Finally, we review the historical influence of Stueckelberg's 1938 idea, which led to applications in many areas not anticipated by the author, such as strings. We describe the numerous proposals to generalize the Stueckelberg trick to the non-Abelian case with the aim to find alternatives to the standard model. Nevertheless, the Higgs mechanism in spontaneous symmetry breaking remains the only presently known way to give masses to non-Abelian vector fields in a renormalizable and unitary theory.Comment: 58 pages, revtex4 RMP format. Added references, minor improvements to tex

Bibliothèque de l’UNIGE - Enquête sur les besoins des usagers

Sur mandat de la Division de l’information scientifique, le groupe « Analyse des besoins » de la Commission tripartite des bibliothèques a mené du 7 octobre au 16 novembre 2013 la première enquête sur les besoins des usagers de la Bibliothèque auprès des membres de la communauté universitaire de Genève. Les résultats obtenus sont exposés dans le présent rapport. Celui-ci comprend quatre parties : une description du sondage, une présentation des données statistiques, une évaluation des résultats obtenus grâce aux données qualitatives (commentaires) et une analyse des commentaires site par site