2017:groups:tools:lhe
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2017:groups:tools:lhe [2017/06/12 17:40] leif.lnnblad |
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| == Splitting up the LHE file == | == Splitting up the LHE file == | ||
| - | The current way of specifying the cross section is not sufficient for some matrix element generators. Requests has been made to be able to report the number of tried events in addition to the ones accepted and actually present in the file. Further more, for practical reasons, there was a request to have the possibility to report the cross section in a separate file, since when starting writing a file, the cross section is not always fully known (this is the case in HepMC where the current best estimate of the cross section is reported for each event. In addition, it is in some cases desirable to divide up a huge LHE file into several smaller ones containing equivalent events. It was therefore decided to allow to split up LHE files into one file containing the ''<init>'' with all information run information, and a list of files containing only ''<event>''s. For this we introduced a new ''<eventfiles>'' tag which may contain an arbitrary number of ''<eventfile>'' tags. The ''<eventfiles>'' tag does not have attributes and must be in the ''<init>'' block. The ''<eventfile>'' the following may be specified. | + | The current way of specifying the cross section is not sufficient for some matrix element generators. Requests has been made to be able to report the number of tried events in addition to the ones accepted and actually present in the file. Further more, for practical reasons, there was a request to have the possibility to report the cross section in a separate file, since when starting writing a file, the cross section is not always fully known (this is the case in HepMC where the current best estimate of the cross section is reported for each event. In addition, it is in some cases desirable to divide up a huge LHE file into several smaller ones containing equivalent events. It was therefore decided to allow to split up LHE files into one file containing the ''<init>'' with all information run information, and a list of files containing only ''<event>'' tags (not enclosed in an ''<LesHouchesEvents>'' tag). For this we introduced a new ''<eventfiles>'' tag which may contain an arbitrary number of ''<eventfile>'' tags. The ''<eventfiles>'' tag does not have attributes and must be in the ''<init>'' block. For the ''<eventfile>'' tag the following attributes may be specified. |
| * ''name'' (mandatory) is the name of the file containing ''<event>''s. This would preferably be a relative filename with respect to the directory where the file containing the ''<init>'' block resides. | * ''name'' (mandatory) is the name of the file containing ''<event>''s. This would preferably be a relative filename with respect to the directory where the file containing the ''<init>'' block resides. | ||
| * ''nevent'' is the number of ''<event>''s in the file. | * ''nevent'' is the number of ''<event>''s in the file. | ||
| * ''ntries'' is the number of attempts the ME generator needed to produce the events in the file. (see below). | * ''ntries'' is the number of attempts the ME generator needed to produce the events in the file. (see below). | ||
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| + | Question: Should not we allow events to be provide as .tar.gz and in that case have a conventional name (like banner.lhe) for the banner file? | ||
| == Cross section information == | == Cross section information == | ||
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| It was agreed that the changes proposed are significant enough to bump the version number of LHE to 4.0. It was also agreed that the LHE accord must be better documented and that there should be one well-defined place to find this documentation. | It was agreed that the changes proposed are significant enough to bump the version number of LHE to 4.0. It was also agreed that the LHE accord must be better documented and that there should be one well-defined place to find this documentation. | ||
| - | Since version 3 of the HepMC event record now comes with sample LHEF code and the option of including LHE information in the HepMC files, it is natural to keep this code up-to-date, and that documentation also is distributed with HepMC3. HepMC3 can be obtained from [[https://gitlab.cern.ch/hepmc/HepMC3]] | + | Since version 3 of the HepMC event record now comes with sample LHEF code and the option of including LHE information in the HepMC files, it is natural to keep this code up-to-date, and that documentation also is distributed with HepMC3. HepMC3 can be obtained from [[https://hepmc.web.cern.ch/hepmc/]]. The modifications suggested here has been implemented in the sample LHEF code available from [[https://gitlab.cern.ch/hepmc/HepMC3]] in the ''LH17'' branch of the HepMC repository. |
2017/groups/tools/lhe.1497282010.txt.gz ยท Last modified: 2017/06/12 17:40 by leif.lnnblad
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