ar X iv : h ep - p h / 05 10 41 4 v 1 3 1 O ct 2 00 5 Sophisticated momenta mapping with DIANA

Details of recent developments of the Feynman diagram analyzer DIANA (DIagram ANAlyser) are presented. Apart from some discussion about QGRAF and new plotting features, we concentrate on a new sophisticated mechanism of momenta mapping. The C-program DIANA (DIagram ANAlyser) for the automatic Feynman diagram evaluation was first documented in [1] 1. Meanwhile there exists a growing series of applications [2] for which DIANA was used. The current DIANA version is 2.37. Here we describe some details of the recent development. 1. Compatibility with current QGRAF versions DIANA uses QGRAF [3] as diagram generator. By now there exist several QGRAF versions which, however, have incompatible syntax of their input files. In most cases the user does not need or does not want to know which version of QGRAF is in use. DIANA takes care of this. It automatically investigates which version of QGRAF is implemented. Starting from version 2.37 it also provides the user with information about the version used for the diagram generation. At present, all QGRAF versions 2. · · · and 3. · · · are supported. From the DIANA point of view there is no difference between them; the differences concern only syntax. 2. New plotting features QGRAF cannot generate two-line vertices. to introduce counterterms. In this case it produces three-line vertices but does not show one of them, i.e. in this case DIANA skips the image of the " spurious " line in the diagram. Another new feature is introduced to suppress labels. In version 2.35 of DIANA and later ones these options (changing the model extensions [4]) are taken into account in terms of " optional extensions " in the propagators of the model file, e.g. in the last two extensions ;nothing,0,0;] (separated by ;) have the following meaning: 1. the new line type of the propagator " nothing " means that this line will not be drawn. The two following parameters in general stand for line characterizations and must be included in any case. 2. the second " extension " apparently is empty, which means that no label will be drawn-in previous versions this meant the " default image " (in the above example: le) 3. Automation of momenta distribution Again, starting from version 2.25, momenta can be introduced automatically. There are several different approaches [5,6]. As " standard " way of attributing momenta, we consider the possibility to calculate, e.g., from external momenta …