Diffraction and Low-Q^2 Physics Including Two-Photon Physics

Recent experimental results on the partonic structure of the photon and on the color singlet exchange in strong interaction processes are reviewed. At the LEP electron-positron and HERA lepton-proton colliders, complementary and consistent measurements have been achieved on the quark-gluon structure of quasi-real and virtual photons. At the HERA lepton-proton and Tevatron proton-antiproton colliders, the quark-gluon configuration of the diffractive exchange is consistently found to have a large gluon component. The rate of diffractive interactions observed by the HERA and Tevatron experiments, however, is largely different and challenges explanation (invited plenary talk at the XXIX International Conference on High Energy Physics, Vancouver, B.C. Canada (1998)).Comment: 36 pages (Latex), 35 figures (Postscript); in this replaced version the report on 'Structure Functions' by A.T.Doyle has been taken out and is available in hep-ex/981202

Neopatrimonialism revisited : beyond a catch-all concept

The article provides a critical discussion of the literature on “patrimonialism” and "neopatrimonialism” as far as the use in Development Studies in general or African Studies in particular is concerned. To overcome the catch-all use of the concept the authors present their own definition of “neopatrimonialism” based on Max Weber’s concept of patrimonialism and legal-rational bureaucracy. However, in order to make the concept more useful for comparative empirical research, they argue, it needs a thorough operationalisation (qualitatively and quantitatively) and the creation of possible subtypes which, in combination, might contribute to a theory of neopatrimonial action.Der Artikel unterzieht die beiden Konzepte „Patrimonialismus“ und „Neopatrimonialismus“, wie sie in der entwicklungstheoretischen Literatur und in Afrikastudien Verwendung finden, einer kritischen Analyse. Damit dem Konzept des Neopatrimonialismus mehr als nur eine heuristische Bedeutung zukommen kann, präsentieren die Autoren eine eigene Definition des Begriffs, die sich eng an die Weber’schen Konzepte des Patrimonialismus und der legal-rationalen Bürokratie anlehnt. Darüber hinaus ist auf dieser Grundlage (1) eine sorgfältige (qualitative und/oder quantitative) Operationalisierung des Konzeptes und (2) die Bildung von möglichen Subtypen notwendig. Erst dann kann das Konzept sinnvoll für die vergleichende empirische Forschung eingesetzt und möglicherweise etwas wie eine neopatrimoniale Handlungstheorie entwickelt werden

Weighted surface algebras: general version

We introduce general weighted surface algebras of triangulated surfaces with arbitrarily oriented triangles and describe their basic properties. In particular, we prove that all these algebras, except the singular disc, triangle, tetrahedral and spherical algebras, are symmetric tame periodic algebras of period 4.Comment: arXiv admin note: text overlap with arXiv:1703.0234

The pricing of lookback options and binomial approximation

Refining a discrete model of Cheuk and Vorst we obtain a closed formula for the price of a European lookback option at any time between emission and maturity. We derive an asymptotic expansion of the price as the number of periods tends to infinity, thereby solving a problem posed by Lin and Palmer. We prove, in particular, that the price in the discrete model tends to the price in the continuous Black-Scholes model. Our results are based on an asymptotic expansion of the binomial cumulative distribution function that improves several recent results in the literature.Comment: 30 page