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Дата изменения: Tue Aug 15 14:21:26 2000 Дата индексирования: Mon Oct 1 22:41:46 2012 Кодировка: |
The View squared diagrams function is similar to
the View diagram one of the previous menu
but is applied to the set of squared diagrams.
Each squared diagram is a graphic representation
of
contribution in the squared matrix element,
where
and
are some amplitudes corresponding to
Feynman diagrams.
Let us summarize some features of CompHEP squared diagrams generation:
If you browse the squared diagrams after usage of the Symbolic calculation function you will see that each of the squared diagrams is marked by one of the following labels CALC, ZERO, Out of memory, Del. They mean that the diagram has been successfully calculated; gives a zero contribution; cannot be calculated; or has been deleted, correspondingly.
The Symbolic calculation function starts symbolic evaluation of the generated squared diagrams. This evaluation is performed by the built-in symbolic calculator created specially in the framework of the CompHEP project.
During the calculation the information about a number of calculated diagrams and about a step of evaluation of the current diagram is shown.
The Reduce program function creates a code of symbolic evaluation in the format of Reduce language [Hearn&Fitch] separately for each squared diagram. These codes are not used for the further CompHEP processing, but they can be useful for cross-checking the CompHEP software. On one hand, one can investigate the Reduce code to get conviction that it correctly calculates a contribution of the squared diagram. On the other hand, you may compare the result of the Reduce evaluation of diagram code with the result of built-in symbolic calculator.
General purpose of a package like CompHEP is to create the
corresponding C or Fortran source code for further numerical
processing and compile this code using the corresponding
system facilities. User's control is not necessary for this step as well as
for the step of symbolic calculations.
CompHEP provides the user with a possibility to perform the above steps
in a non-interactive mode. To start the non-interactive session one could activate
the Make n_comphep_c or Make n_comphep_f
menu function. Then the current interactive session ends and a
new batch process starts. See Section
for details of the non-interactive calculations in CompHEP.
As the outcome, the executable file n_comphep_c or n_comphep_f is created for the further numerical precessing. You may find it in the results directory. For the time of batch calculation the LOCK file appears in the user working directory to prevent a double start of the CompHEP package within the same place of the file system.
As a rule the System Administrator requires to start a large job in a special batch regime. The execution of one of the Make n_comphep_ functions may require large computer resources for some processes with large number of diagrams. In this case you could correct your comphep command file according to the System Administrator rules. The corresponding calls are disposed after labels 24) and 25) in this file.