Application of the Worldline Path Integral Method to the Calculation of Inverse Mass Expansions

Higher order coefficients of the inverse mass expansion of one-loop effective actions are obtained from a one-dimensional path integral representation. For the case of a massive scalar loop in the background of both a scalar potential and a (non Abelian) gauge field explicit results to $O(T^5)$ in the proper time parameter are presented.Comment: 6 pages, LaTeX. Talk given at 5th International Workshop on Software Engineering and Artificial Intelligence for High Energy and Nuclear Physics (AIHENP96), Lausanne (Switzerland), 2-6 September 199

Resummed effective action in the world-line formalism

Using the world-line method we resum the scalar one-loop effective action. This is based on an exact expression for the one-loop action obtained for a background potential and a Taylor expansion of the potential up to quadratic order in x-space. We thus reproduce results of Masso and Rota very economically. An alternative resummation scheme is suggested using ``center of mass'' based loops which is equivalent under the assumption of vanishing third and higher derivatives in the Taylor expansion but leads to simplified expressions. In an appendix some general issues concerning the relation between world-line integrals with fixed end points versus integrals with fixed center are clarified. We finally note that this method is also very valuable for gauge field effective actions where it is based on the Euler--Heisenberg type resummation.Comment: 15 page

Determinant Calculations Using Random Walk Worldline Loops

We use statistical ensembles of worldline loops generated by random walk on hypercubic lattices to calculate matter determinants in background Yang-Mills fields.Comment: 3 pages, 3 ps figures, Lattice2002 (algor

Effective Action in a General Chiral Model: Next to Leading Order Derivative Expansion in the Worldline Method

We present a formalism to determine the imaginary part of a general chiral model in the derivative expansion. Our formalism is based on the worldline path integral for the covariant current that can be given in an explicit chiral and gauge covariant form. The effective action is then obtained by integrating the covariant current, taking account of the anomaly.Comment: 33 pages, minor changes, published versio

An Improved Heat Kernel Expansion from Worldline Path Integrals

The one--loop effective action for the case of a massive scalar loop in the background of both a scalar potential and an abelian or non--abelian gauge field is written in a one--dimensional path integral representation. From this the inverse mass expansion is obtained by Wick contractions using a suitable Green function, which allows the computation of higher order coefficients. For the scalar case, explicit results are presented up to order O(T**8) in the proper time expansion. The relation to previous work is clarified.Comment: 13 pages, Plain TEX, no figure

Charakteristika prämierter Forschung in der deutschsprachigen Sozialwissenschaft. Eine Analyse der mit dem Preis der Fritz Thyssen Stiftung ausgezeichneten sozialwissenschaftlichen Aufsätze 1981-2006

Der Beitrag fasst zentrale Ergebnisse eines von der Fritz Thyssen Stiftung finanzierten Pilotprojekts über die Auszeichnung sozialwissenschaftlicher deutschsprachiger Zeitschriftenartikel mit dem Fritz Thyssen Preis im Zeitraum 1981 bis 2006 zusammen. Vorrangig geht es um die Klärung von vier Grundfragen: (1) Welches sind die Merkmale prämierter Aufsätze und welche Merkmalverschiebungen ergeben sich im Zeitraum der letzten 25 Jahre? (2) Inwieweit korreliert das Distinktionsmerkmal "Thyssen-Preis" mit anderen Merkmalen der Distinktion von Autoren, die in der Evaluationsforschung Verwendung finden? (3) In welchem Maße konzentriert sich preisgekrönte Forschung auf einige wenige Standorte? (4) Welche Zeitschriften und welche Formen der Sozialwissenschaft schneiden besonders gut ab? Die Analyse konzentriert sich damit auf vier Ebenen, nämlich die Autoren und ihre institutionellen Standorte, die inhaltliche Ausrichtung der prämierten Artikel sowie die Ebene der am Wettbewerb teilnehmenden Zeitschriften. Zu den zentralen Ergebnissen zählt, dass verschiedene Distinktionsmerkmale in den Sozialwissenschaften nur sehr schwach korreliert sind und dass auch preisgekrönte deutsche Sozialforschung international nur schwach sichtbar ist.Based on a research project financed by the Fritz Thyssen Foundation, this report analyzes the characteristics of German social science publications which were awarded the Fritz Thyssen Prize in the period 1981-2006. This prize is annually awarded to the best social science articles published in German language social science journals. Four questions are dealt with: (1) How did the characteristics of the articles which were awarded the prize change over time? (2) To what extent is the receipt of the award correlated with other criteria of distinction which are used for evaluation purposes? (3) To what extent is research leading to the prize concentrated in a few outstanding research institutes? (4) Which journals and which types of social science are most successful? The analysis thus focuses on four levels, i.e. the level of the authors, of the institutes they are affiliated with, the levels of the articles and their content, and the level of the journals participating in the contest. Two key findings are that different criteria of success in social science evaluations are only weakly correlated and that German speaking social science publications have a low level of international visibility even if awarded with a prestigious prize