JaxoDraw is a Feynman graph plotting tool written in Java. It has a complete graphical user interface that allows all actions to be carried out via mouse click-and-drag operations in a WYSIWYG fashion. Graphs may be exported to postscript/EPS format and can be saved in XML files to be used in later sessions. One of the main features of JaxoDraw is the possibility to produce LaTeX code that may be used to generate graphics output, thus combining the powers of TeX/LaTeX with those of a modern day drawing program. With JaxoDraw it becomes possible to draw even complicated Feynman diagrams with just a few mouse clicks, without the knowledge of any programming language.Comment: 15 pages, no figures; typos corrected; visit the JaxoDraw home page at http://altair.ific.uv.es/~JaxoDraw/home.htm

A new version of the Feynman graph plotting tool JaxoDraw is presented. Version 2.0 is a fundamental re-write of most of the JaxoDraw core and some functionalities, in particular importing graphs, are not backward-compatible with the 1.x branch. The most prominent new features include: drawing of Bézier curves for all particle modes, on-the-fly update of edited objects, multiple undo/redo functionality, the addition of a plugin infrastructure, and a general improved memory performance. A new LaTeX style file is presented that has been written specifically on top of the original axodraw.sty to meet the needs of this this new version. PROGRAM SUMMARYTitle of program: JaxoDraw Distribution format: gzipped tar archive Operating system: Any Java-enabled platform, tested on Linux, Windows XP, Mac OS X Keywords: Feynman diagrams, L A T E X, Java, GUI Programming language used: Java License: GPL Catalogue identifier of previous version: ADUA Journal Reference of previous version: Comput. Phys. Commun. 161 (2004) 76-86 Does the new version supersede the previous version?: Yes Nature of problem:Existing methods for drawing Feynman diagrams usually require some 'hardcoding' in one or the other programming-or scripting language. It is not very convenient and often time consuming, to generate relatively simple diagrams. Method of solution:A program is provided that allows for the interactive drawing of Feynman diagrams with a graphical user interface. The program is easy to learn and use, produces high quality output in several formats and runs on any operating system where a Java Runtime Environment is available. Reasons for the new version:A variety of new features and bug fixes. Summary of revisions:Major revisions since the last published user guide were versions 1.1, 1.2 and 1.3 with several minor bug-fix releases in between. Restrictions:To make use of the latex export/preview functionality, a latex style file has to be installed separately. Certain operations (like internal latex compilation, Postscript preview) require the execution of external commands that might not work on untested operating systems. Typical running time: As an interactive program, the running time depends on the complexity of the diagram to be drawn.

π and η decay modes of light baryon resonances are investigated within a chiral quark model whose hyperfine interaction is based on Goldstone-boson exchange. For the decay mechanism a modified version of the 3 P0 model is employed. Our primary aim is to provide a further test of the recently proposed Goldstone-boson-exchange constituent quark model. We compare the predictions for π and η decay widths with experiment and also with results from a traditional one-gluon-exchange constituent quark model. The differences between nonrelativistic and semirelativistic versions of the constituent quark models are outlined. We also discuss the sensitivity of the results on the parametrization of the meson wave function entering the 3 P0 model.

The effect of different boost expressions is considered for the calculation of the ground-state form factor of a two-body system made of scalar particles interacting via the exchange of a scalar boson. The aim is to provide an uncertainty range on methods employed in implementing these effects as well as an insight on their relevance when an "exact" calculation is possible. Using a wave function corresponding to a mass operator that has the appropriate properties to construct the generators of the Poincaré algebra in the framework of relativistic quantum mechanics, form factors are calculated using the boost transformations pertinent to the instant, front and point forms of this approach. Moderately and strongly bound systems are considered with masses of the exchanged boson taken as zero, 0.15 times the constituent mass m, and infinity. In the first and last cases, a comparison with "exact" calculations is made (Wick-Cutkosky model and Feynman triangle diagram). Results with a Galilean boost are also given. Momentum transfers up to Q 2 = 100 m 2 are considered. Emphasis is put on the contribution of the single-particle current, as usually done. It is found that the present point-form calculations of form factors strongly deviate from all the other ones, requiring large contributions from two-body currents. Different implementations of the point-form approach, where the role of these two-body currents would be less important, are sketched.

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The electromagnetic form factor of the pion is calculated in the "point-form" of relativistic quantum mechanics using simple, phenomenological wave functions. It is found that the squared charge radius of the pion is predicted one order of magnitude larger than the experimental value and the asymptotic behavior expected from QCD cannot be reproduced. The origin of these discrepancies is analyzed. The present results confirm previous ones obtained from a theoretical model and call for major improvements in the implementation of the "point-form" approach.PACS numbers: 13.40. Gp, 12.39.Ki, 14.40.Aq * Electronic address: desplanq@isn.in2p3.fr † Electronic address: Lukas.Theussl@uv.es 1 As it has been observed in our recent work [16,17,18] and in Ref. [19], this implementation is not identical to the form proposed by Dirac [20] in that it does not involve a quantization performed on a hyperboloid. To emphasize this difference, we will put the expression "point-form" between quotation marks throughout this paper.

An effective formalism is developed to handle decaying two-state systems. Herewith, observables of such systems can be described by a single operator in the Heisenberg picture. This allows for using the usual framework in quantum information theory and, hence, to enlighten the quantum feature of such systems compared to non-decaying systems. We apply it to systems in high energy physics, i.e. to oscillating meson-antimeson systems. In particular, we discuss the entropic Heisenberg uncertainty relation for observables measured at different times at accelerator facilities including the effect of CP violation, i.e. the imbalance of matter and antimatter. An operator-form of Bell inequalities for systems in high energy physics is presented, i.e. a Bell-witness operator, which allows for simple analysis of unstable systems.

We calculate generalized parton distribution functions in a field theoretic formalism using a covariant Bethe-Salpeter approach for the determination of the bound-state wave function. We describe the procedure in an exact calculation in scalar Electrodynamics proving that the relevant corrections outside our scheme vanish. We extend the formalism to the Nambu-Jona-Lasinio model, a realistic theory of the pion. We go in both cases beyond all previous calculations and discover that all important features required by general physical considerations, like symmetry properties, sum rules and the polynomiality condition, are explicitly verified. We perform a numerical study of their behavior in the weak and strong coupling limits.