ar X iv : h ep - t h / 05 01 10 4 v 1 1 4 Ja n 20 05 New Constructions in Local Quantum Physics ∗

Among several ideas which arose as consequences of modular localization there are two proposals which promise to be important for the classification and construction of QFTs. One is based on the observation that wedge-localized algebras may have particle-like generators with simple properties and the second one uses the structural simplification of wedge-localized algebras in the holographic lightfront projection. Factorizable d=1+1 models permit to analyse the interplay between particle-like aspects and chiral field properties of lightfront holography. Pacs 11.10.-z, 11.55.-m 1 How modular theory entered particle physics The following introductory remarks about the history and the physical content of modular theory are intended to be helpful to understand the recent role of modular localization in the classification and construction of models of QFT without the use of Lagrangian quantization. 1.1 Remarks about history of modular localization The beginnings of modular theory date back to the second half of the 1960s when two independent ideas, one from mathematics and one from particle physics, merged together [1]. On the mathematical side the Japanese mathematician Tomita generalized a concept, which before was only studied in the special context of the Haar measure (”unimodular”) in group algebra theory, to the general setting of von Neumann algebras. At the same time three physicists, Haag, Hugenholtz and Winnink [2], found a conceptual framework for the direct field theoretic description of the thermodynamic limit (“open systems”) in terms Talk presented at “Rigorous quantum field theory”, symposium in honor of J. Bros, Paris, July 2004