Browsing by Author Schroer, Bert


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Constructive use of holographic projectionsSchroer, Bert-2008-
Do confinement and darkness have the same conceptual roots?Schroer, Bert-2008Indecomposable positive energy quantum matter comes in 3 forms: one massive and two massless families of which about the so called "infinite spin" family was little known up to recently. Using novel methods which are particularly suited for problems of localization, it was shown that this quantum matter of the third kind cannot be generated by pointlke localized fields but rather needs semiinfinite stringlike generators. Arguing that the field algebras generated by these new objects do not possess any compactly localizable subalgebras, we are led to a situation of purely gravitating matter which cannot be registered in any particle counter i.e. to observational darkness and possibly also inertness. \ A milder form of darkness which only blackouts certain string localized objects but leaves a large observable subalgebra generated by pointlike fields occurs with interacting zero mass finite helicity matter and it is the main aim of this note to emphasize these analogies.
A note on infraparticles and unparticlesSchroer, BertCentro Brasileiro de Pesquisas Físicas (CBPF)2008We remind the reader of the meaning and achievements of infraparticles which, although themselves not necessarily of zero mass, require the presence of zero mass in order get delocalized states with a singularity which dissolves the mass-shell in an inexorable way into the continuum and therefore renders the standard particle concept useless. These objects were recently rediscovered under the name unparticles The case of infraparticles also encompasses particle-like objects in conformal QFT when all multiparticle thresholds coalesce on top of each other and only the concept of a highly inclusive cross section survives of scattering theory. The infraparticle research has led to deep results and the recently discovered semiinfinite string-localized vectorpotentials have led to new interesting ideas of dealing with physical electrically charged states and a generalized scattering theory. We explain why unparticles are identical to the old infraparticles. Using this relation it is shown that unparticles/infraparticles cannot lead to a natural description of darkness of dark matter. A more radical scenario for darkness comes from semiinfinite string-localized vectorpotentials in a reformulated version of nonabelian gauge theory.
Particle physics in the 60 and 70 and the legacy of contributions by J. A. SwiecaSchroer, Bert-2007After revisiting some high points of particle physics and QFT of the two decades from 1960 to 1980, I comment on the work by Jorge Andr'e Swieca. I explain how it fits into the development of QFT during these two decades and draw attention to its legacy in the ongoing particle physics research.